Lumentum (LITE) 10-Q 2 Feb 21 2021 Q2 Quarterly report Financial data

COVER

COVER - shares shares in Millions	6 Months Ended
	Dec. 26, 2020	Jan. 26, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 26, 2020
Document Transition Report	false
Entity File Number	001-36861
Entity Registrant Name	Lumentum Holdings Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-3108385
Entity Address, Address Line One	1001 Ridder Park Drive
Entity Address, City or Town	San Jose
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95131
City Area Code	408
Local Phone Number	546-5483
Title of 12(b) Security	Common Stock, par value of $0.001 per share
Trading Symbol	LITE
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		75.7
Entity Central Index Key	0001633978
Amendment Flag	false
Current Fiscal Year End Date	--07-03
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Income Statement [Abstract]
Net revenue	$ 478.8	$ 457.8	$ 931.2	$ 907.7
Cost of sales	234.2	256.3	465.9	526
Amortization of acquired developed intangibles	15	12.4	30	24.9
Gross profit	229.6	189.1	435.3	356.8
Operating expenses:
Research and development	52.8	51	103.2	100.9
Selling, general and administrative	61.3	62.4	117.6	119.1
Restructuring and related charges	0.2	0.9	0.2	2.2
Total operating expenses	114.3	114.3	221	222.2
Income from operations	115.3	74.8	214.3	134.6
Interest expense	(16.3)	(18.3)	(32.3)	(29.7)
Other income (expense), net	(0.9)	1.2	(0.3)	6.2
Income before income taxes	98.1	57.7	181.7	111.1
Provision for income taxes	14.9	8.6	31.4	14.4
Net income	$ 83.2	$ 49.1	$ 150.3	$ 96.7
Net income per share:
Basic (in usd per share)	$ 1.10	$ 0.64	$ 1.99	$ 1.26
Diluted (in usd per share)	$ 1.06	$ 0.63	$ 1.92	$ 1.24
Shares used to compute net income per share:
Basic (in shares)	75.6	76.8	75.5	76.9
Diluted (in shares)	78.4	78	78.3	77.8

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 83.2	$ 49.1	$ 150.3	$ 96.7
Other comprehensive loss, net of tax:
Net change in unrealized loss on available-for-sale securities	(0.4)	(0.2)	(1.9)	(0.1)
Other comprehensive loss, net of tax	(0.4)	(0.2)	(1.9)	(0.1)
Comprehensive income, net of tax	$ 82.8	$ 48.9	$ 148.4	$ 96.6

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Current assets:
Cash and cash equivalents	$ 321.3	$ 298
Short-term investments	1,379	1,255.8
Accounts receivable, net	276.7	233.5
Inventories	207.1	188.9
Prepayments and other current assets	82.1	73.8
Total current assets	2,266.2	2,050
Property, plant and equipment, net	385.8	393
Operating lease right-of-use assets, net	71.8	78.7
Goodwill	368.9	368.9
Other intangible assets, net	285.2	316.8
Deferred income taxes	84.9	81.2
Other non-current assets	5.4	4
Total assets	3,468.2	3,292.6
Current liabilities:
Accounts payable	111.3	150.8
Accrued payroll and related expenses	46.9	53.4
Accrued expenses	32.7	23.7
Convertible notes, current	380.3	0
Operating lease liabilities, current	10.8	10.8
Other current liabilities	65.3	44.3
Total current liabilities	647.3	283
Convertible notes, non-current	769.1	1,120.3
Operating lease liabilities, non-current	55.1	57.6
Deferred tax liability	36.7	46.5
Other non-current liabilities	38.1	36
Total liabilities	1,546.3	1,543.4
Commitments and contingencies (Note 14)
Stockholders’ equity:
Common stock, $0.001 par value, 990 authorized shares, 75.7 and 75.1 shares issued and outstanding as of December 26, 2020 and June 27, 2020, respectively	0.1	0.1
Additional paid-in capital	1,700.9	1,676.6
Retained earnings	214.9	64.6
Accumulated other comprehensive income	6	7.9
Total stockholders’ equity	1,921.9	1,749.2
Total liabilities and stockholders’ equity	$ 3,468.2	$ 3,292.6

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 26, 2020	Jun. 27, 2020
Statement of Financial Position [Abstract]
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, authorized shares (in shares)	990,000,000	990,000,000
Common stock, shares issued (in shares)	75,700,000	75,100,000
Common stock, shares outstanding (in shares)	75,700,000	75,100,000

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period at Jun. 29, 2019	$ 1,497.1	$ 0.1	$ 1,360.8	$ 129.1	$ 7.1
Balance at the beginning of period (in shares) at Jun. 29, 2019		76.7
Increase (Decrease) in Stockholders' Equity
Net income	47.6			47.6
Other comprehensive loss	0.1				0.1
Issuance of shares pursuant to equity plans, net of tax withholdings (in shares)		0.5
Stock-based compensation	16.5		16.5
Balance at the end of the period at Sep. 28, 2019	1,561.3	$ 0.1	1,377.3	176.7	7.2
Balance at the end of period (in shares) at Sep. 28, 2019		77.2
Balance at the beginning of the period at Jun. 29, 2019	1,497.1	$ 0.1	1,360.8	129.1	7.1
Balance at the beginning of period (in shares) at Jun. 29, 2019		76.7
Increase (Decrease) in Stockholders' Equity
Net income	96.7
Other comprehensive loss	(0.1)
Balance at the end of the period at Dec. 28, 2019	1,681.6	$ 0.1	1,648.7	25.8	7
Balance at the end of period (in shares) at Dec. 28, 2019		74.7
Balance at the beginning of the period at Sep. 28, 2019	1,561.3	$ 0.1	1,377.3	176.7	7.2
Balance at the beginning of period (in shares) at Sep. 28, 2019		77.2
Increase (Decrease) in Stockholders' Equity
Net income	49.1			49.1
Other comprehensive loss	(0.2)				(0.2)
Issuance of shares pursuant to equity plans, net of tax withholdings (in shares)		0.3
Exercise of stock options	0.3		0.3
Equity component of the 2026 Notes, net of tax of $67.0 million and issuance costs of $2.3 million	245.9		245.9
ESPP shares issued	4.9		4.9
ESPP shares issued (in shares)		0.1
Repurchases of common stock	(200)			(200)
Repurchases of common stock (in shares)		(2.9)
Stock-based compensation	20.3		20.3
Balance at the end of the period at Dec. 28, 2019	1,681.6	$ 0.1	1,648.7	25.8	7
Balance at the end of period (in shares) at Dec. 28, 2019		74.7
Balance at the beginning of the period at Jun. 27, 2020	1,749.2	$ 0.1	1,676.6	64.6	7.9
Balance at the beginning of period (in shares) at Jun. 27, 2020		75.1
Increase (Decrease) in Stockholders' Equity
Net income	67.1			67.1
Other comprehensive loss	(1.5)				(1.5)
Issuance of shares pursuant to equity plans, net of tax withholdings	(19.1)		(19.1)
Issuance of shares pursuant to equity plans, net of tax withholdings (in shares)		0.4
Exercise of stock options	0.1		0.1
Stock-based compensation	20.3		20.3
Balance at the end of the period at Sep. 26, 2020	1,816.1	$ 0.1	1,677.9	131.7	6.4
Balance at the end of period (in shares) at Sep. 26, 2020		75.5
Balance at the beginning of the period at Jun. 27, 2020	1,749.2	$ 0.1	1,676.6	64.6	7.9
Balance at the beginning of period (in shares) at Jun. 27, 2020		75.1
Increase (Decrease) in Stockholders' Equity
Net income	150.3
Other comprehensive loss	(1.9)
Balance at the end of the period at Dec. 26, 2020	1,921.9	$ 0.1	1,700.9	214.9	6
Balance at the end of period (in shares) at Dec. 26, 2020		75.7
Balance at the beginning of the period at Sep. 26, 2020	1,816.1	$ 0.1	1,677.9	131.7	6.4
Balance at the beginning of period (in shares) at Sep. 26, 2020		75.5
Increase (Decrease) in Stockholders' Equity
Net income	83.2			83.2
Other comprehensive loss	(0.4)
Issuance of shares pursuant to equity plans, net of tax withholdings	(7.1)		(7.1)
Issuance of shares pursuant to equity plans, net of tax withholdings (in shares)		0.1
ESPP shares issued	5.5		5.5
ESPP shares issued (in shares)		0.1
Stock-based compensation	24.6		24.6
Balance at the end of the period at Dec. 26, 2020	$ 1,921.9	$ 0.1	$ 1,700.9	$ 214.9	$ 6
Balance at the end of period (in shares) at Dec. 26, 2020		75.7

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - 2026 Notes - Convertible Debt $ in Millions	3 Months Ended
	Dec. 28, 2019USD ($)
Equity component	$ 67
Debt issuance costs	$ 2.3

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019
OPERATING ACTIVITIES:
Net income	$ 150.3	$ 96.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	47.6	60.3
Stock-based compensation	43.6	36.9
Loss on early extinguishment of debt	0	8
Amortization of acquired intangibles	41.6	37.4
Loss on disposal of property, plant and equipment	4.7	4.7
Amortization of debt discount and debt issuance costs	29.1	11.3
Amortization of inventory fair value adjustment in connection with Oclaro acquisition	0	4.3
Other non-cash expense (income)	3.8	(0.5)
Changes in operating assets and liabilities:
Accounts receivable	(43.7)	(54)
Inventories	(16.9)	44.3
Operating lease right-of-use assets, net	6.9	6.6
Prepayments and other current and non-currents assets	(9.8)	4.8
Income taxes, net	11	10.4
Accounts payable	(35.8)	(18.7)
Accrued payroll and related expenses	(6.5)	11.4
Operating lease liabilities	(2.5)	(6.9)
Accrued expenses and other current and non-current liabilities	9.8	(7.2)
Net cash provided by operating activities	233.2	249.8
INVESTING ACTIVITIES:
Payments for acquisition of property, plant and equipment	(50.5)	(47.4)
Payment for asset acquisition	(10)	(3)
Proceeds from sale of product lines	1.3	2.5
Purchases of short-term investments	(952.2)	(51.3)
Proceeds from maturities and sales of short-term investments	822.4	157
Net cash (used in) provided by investing activities	(189)	57.8
FINANCING ACTIVITIES:
Repurchase of common stock	0	(200)
Proceeds from the issuance of 0.50% Convertible Notes due 2026, net of issuance costs	0	1,042.9
Tax payments related to restricted stock	(26.2)	0
Proceeds from employee stock plans	5.5	4.9
Principal payments on finance leases	(0.3)	(5.8)
Proceeds from the exercise of stock options	0.1	0.3
Repayment of term loan	0	(497.5)
Net cash (used in) provided by financing activities	(20.9)	344.8
Increase in cash and cash equivalents	23.3	652.4
Cash and cash equivalents at beginning of period	298	432.6
Cash and cash equivalents at end of period	321.3	1,085
Supplemental disclosure of cash flow information:
Cash paid for taxes	20.5	3.9
Cash paid for interest	3.2	10.2
Supplemental disclosure of non-cash transactions:
Unpaid property, plant and equipment in accounts payable and accrued expenses	6.9	9.4
Issuance costs in current liabilities	0	0.7
Right-of-use assets obtained in exchange for new operating lease liabilities	0	2.2
Net transfer of assets from property plant and equipment to assets held-for-sale	$ 0	$ 2.1

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)	Dec. 26, 2020	Dec. 31, 2019	Dec. 28, 2019
2026 Notes | Convertible Debt
Debt Instrument
Debt, stated interest rate	0.50%	0.50%	0.50%

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	6 Months Ended
	Dec. 26, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	Note 1. Description of Business and Summary of Significant Accounting Policies Description of Business Lumentum Holdings Inc. (“we,” “us,” “our”, “Lumentum” or the “Company”) is an industry-leading provider of optical and photonic products defined by revenue and market share addressing a range of end market applications including Optical Communications (“OpComms”) and Commercial Lasers (“Lasers”) for manufacturing, inspection and life-science applications. We seek to use our core optical and photonic technology, and our volume manufacturing capability, to expand into attractive emerging markets that benefit from advantages that optical or photonics-based solutions provide, including 3D sensing for consumer electronics and diode light sources for a variety of consumer and industrial applications. The majority of our customers tend to be original equipment manufacturers (“OEMs”) that incorporate our products into their products which then address end-market applications. For example, we sell fiber optic components that network equipment manufacturers (“NEMs”) assemble into communications networking systems, which they sell to network service providers, operators or enterprises with their own networks. Similarly, many of our customers for our Lasers products incorporate our products into tools they produce, which are used for manufacturing processes by their customers. For 3D sensing, we sell diode lasers to manufacturers of consumer electronics products for mobile, personal computing, gaming, and other applications who then integrate our devices within their products, for eventual resale to consumers and also into other industrial applications. Basis of Presentation The preparation of the condensed consolidated financial statements in accordance with U.S. generally accepted accounting principles (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in our condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and various other assumptions believed to be reasonable. Although these estimates are based on management’s best knowledge of current events and actions that may impact the Company in the future, actual results may be different from the estimates. Our critical accounting policies are those that affect our financial statements materially and involve difficult, subjective or complex judgments by management. Those policies are inventory valuation, revenue recognition, income taxes, and goodwill. The COVID-19 pandemic has created and may continue to create significant uncertainty in global financial markets, which has disrupted and harmed, and may continue to disrupt and harm, the Company's business, financial condition, and results of operations. The extent of the impact of COVID-19 on the Company's operational and financial performance will depend on certain developments, including but not limited to the duration and spread of the outbreak, duration of local, state and federal issued public health orders in each jurisdiction where we operate or in which our customers and suppliers operate, impact on our customers and our sales cycles, impact on our supply chain and manufacturing partners, impact on our employees and impact on regional and worldwide economies and financial markets in general, all of which are uncertain and cannot be predicted. Fiscal Years We utilize a 52-53 week fiscal year ending on the Saturday closest to June 30th. Every fifth or sixth fiscal year will have a 53-week period. The additional week in a 53-week year is added to the third quarter, making such quarter consist of 14 weeks. Our fiscal 2021 is a 53-week year ending on July 3, 2021, with the quarter ended December 26, 2020 being a 13-week quarterly period and our third quarter ending on April 3, 2021 being a 14-week quarterly period. Our fiscal 2020 was a 52-week year that ended on June 27, 2020, with the quarter ended December 28, 2019 being a 13-week quarterly period. Principles of Consolidation These interim unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All inter-company transactions and balances have been eliminated in consolidation. Accounting Policies The accompanying condensed consolidated financial statements and accompanying related notes should be read in conjunction with the audited consolidated financial statements and related notes included in our Annual Report on Form 10-K for the fiscal year ended June 27, 2020. There have been no significant changes to these policies during the six months ended December 26, 2020, except for the removal of the long-lived asset valuation policy and the updates resulting from the adoption of Topic 326,

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	6 Months Ended
	Dec. 26, 2020
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Pronouncements	Note 2. Recently Issued Accounting Pronouncements Accounting Pronouncements Recently Adopted In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 modifies the disclosure requirements on transfers between Level 1 and Level 2, valuation processes of Level 3 fair value measurements, and the categorization by level for items that are not measured at fair value, but for which the fair value is required to be disclosed. We adopted ASU 2018-13 in the first quarter of fiscal 2021 with no impact to our condensed consolidated financial statements. In August 2018, FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. This standard requires capitalization of the implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. Further, the standard also requires the Company to expense the capitalized implementation costs of a hosting arrangement over the term of the hosting arrangement. We adopted ASU 2018-15 in the first quarter of fiscal 2021 with no impact to our condensed consolidated financial statements. In June 2016, FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments and a subsequent amendment, ASU 2018-19 (collectively, Topic 326). Topic 326 requires measurement and recognition of expected credit losses for financial assets held. We adopted ASU 2016-13 using the modified-retrospective approach in the first quarter of fiscal 2021 with no material impact to our condensed consolidated financial statements. With the adoption of Topic 326, we are now assessing whether unrealized losses have resulted from a credit loss or other factors. We believe none of our unrealized losses on available-for-sale investments were other-than temporary or were attributable to credit losses as of December 26, 2020 and June 27, 2020. We review our available-for-sale investments on a quarterly basis to identify a potential other-than-temporary impairment. The investments with unrealized losses consisted primarily of corporate debt securities, and given the extent of the unrealized loss positions, the issuers' high credit ratings and the near-term market conditions, we believe our unrealized losses are temporary. We also do not have an intent to sell our investments and would not be required to sell them before they recover. The adoption of Topic 326 did not significantly change our approach to the valuation of trade receivables. We determine whether there is an expected loss on our accounts receivable by reviewing all available data, including our customers' latest available financial statements, their credit standing and historical collection experience, as well as current and future market and economic conditions. As of December 26, 2020 and June 27, 2020, the allowance for credit losses on our trade receivables was $1.7 million and $1.8 million, respectively. Accounting Pronouncements Not Yet Effective In August 2020, FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , which simplifies the accounting for convertible instruments by removing the separation models for (1) convertible debt with a cash conversion feature and (2) convertible instruments with a beneficial conversion feature. As a result, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost. Also, ASU 2020-06 requires the application of the if-converted method for calculating diluted earnings per share and the treasury stock method will be no longer available. The new guidance is effective for fiscal years beginning after December 15, 2021, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. ASU 2020-06 is effective for us in our first quarter of fiscal year 2023. We are currently evaluating the impact of ASU 2020-06 on our condensed consolidated financial statements. In December 2019, FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (Topic 740), which is intended to simplify various aspects related to accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and which also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for us at the beginning of fiscal year 2022, including interim periods within that reporting period, although early adoption is permitted. We are currently evaluating the impact of ASU 2019-12 on our condensed consolidated financial statements. In August 2018, FASB issued ASU 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans . ASU 2018-14 modifies the disclosure requirements for defined benefit pension plans and other post-retirement benefit plans. The new guidance is effective for fiscal years ending after December 15, 2020, with early adoption permitted. ASU 2018-14 should be applied retrospectively to all periods presented and is effective for us in our fourth quarter of fiscal year 2021 as ASU 2018-14 does not amend the interim disclosure requirements. We are currently evaluating the impact of ASU 2018-14 on our condensed consolidated financial statements.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Dec. 26, 2020
Earnings Per Share [Abstract]
Earnings Per Share	Note 3. Earnings Per Share The following table sets forth the computation of basic and diluted net income per share ( in millions, except per share data ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Numerator: Net income $ 83.2 $ 49.1 $ 150.3 $ 96.7 Denominator: Basic weighted average common shares outstanding 75.6 76.8 75.5 76.9 Effect of dilutive securities from stock-based benefit plans 0.7 0.7 0.8 0.7 Shares issuable assuming conversion of the 2024 Notes 2.1 0.5 2.0 0.2 Diluted weighted average common shares outstanding 78.4 78.0 78.3 77.8 Net income per share: Basic $ 1.10 $ 0.64 $ 1.99 $ 1.26 Diluted $ 1.06 $ 0.63 $ 1.92 $ 1.24 Potentially dilutive common shares result from the assumed exercise of outstanding stock options, assumed vesting of outstanding equity awards, assumed issuance of stock under the employee stock purchase plan, and assumed conversion of our outstanding convertible notes, all using the treasury stock method. We have the ability and intent to settle the face value of our convertible notes in cash. Therefore, we use the treasury stock method for calculating the dilutive impact of the convertible not es. The 2026 Notes (as defined in Note 9) will have no impact on diluted earnings per share until the average price of our common stock exceeds the conversion price of $99.29. The potentially dilutive shares resulting from the 2024 Notes (as defined in Note 9) were in cluded in the calculation of diluted income per share for the three and six months ended December 26, 2020 since the average price of our common stock exceeded the conversion price of $60.62. Refer to “Note 9. Debt” for further discussion. Anti-dilutive potential shares are excluded from the calculation of diluted earnings per share if their exercise price exceeded the average market price during the period or the share-based awards were determined to be anti-dilutive based on applying the treasury stock method. Anti-dilutive shares excluded from the calculation of diluted earnings per share were not material and 0.5 million shares for the three and six months ended December 26, 2020, respectively. Anti-dilutive shares excluded from the calculation of diluted earnings per share were not material for the three and six months ended December 28, 2019, respectively.

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-term Investments	6 Months Ended
	Dec. 26, 2020
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Short-term Investments	Note 4. Cash, Cash Equivalents and Short-term Investments The following table summarizes our cash, cash equivalents and short-term investments by category for the periods presented ( in millions ): Amortized Gross Gross Fair Value December 26, 2020: Cash $ 107.7 $ — $ — $ 107.7 Cash equivalents: Commercial paper 10.0 — — 10.0 Money market funds 203.6 — — 203.6 Total cash and cash equivalents $ 321.3 $ — $ — $ 321.3 Short-term investments: Certificates of deposit $ 4.9 $ — $ — $ 4.9 Commercial paper 112.8 — — 112.8 Corporate debt securities 523.2 0.5 (0.2) 523.5 U.S. Agency securities 60.6 — — 60.6 U.S. Treasury securities 677.0 0.2 — 677.2 Total short-term investments $ 1,378.5 $ 0.7 $ (0.2) $ 1,379.0 June 27, 2020: Cash $ 114.2 $ — $ — $ 114.2 Cash equivalents: Money market funds 159.6 — — 159.6 U.S. Treasury securities 24.2 — — 24.2 Total cash and cash equivalents $ 298.0 $ — $ — $ 298.0 Short-term investments: Certificates of deposit $ 12.9 $ — $ — $ 12.9 Commercial paper 179.9 0.3 — 180.2 Corporate debt securities 435.0 1.7 (0.1) 436.6 Foreign government bonds 1.7 — — 1.7 U.S. Agency securities 59.5 — — 59.5 U.S. Treasury securities 563.9 1.0 — 564.9 Total short-term investments $ 1,252.9 $ 3.0 $ (0.1) $ 1,255.8 We use the specific-identification method to determine any realized gains or losses from the sale of our short-term investments classified as available-for-sale. During the three and six months ended December 26, 2020 and December 28, 2019, we did not realize significant gains or losses on a gross level from the sale of our short-term investments classified as available-for-sale. During the three and six months ended December 26, 2020, our other income (expense), net was $(0.9) million and $(0.3) million, respectively, and includes interest income on cash equivalents and short-term investments of $1.5 million and $3.9 million, respectively. During the three and six months ended December 28, 2019, our other income (expense), net was $1.2 million and $6.2 million, respectively, and includes interest income on cash equivalents and short-term investments of $3.4 million and $7.4 million, respectively. We included $5.2 million and $4.3 million of interest receivable in prepayments and other current assets as of December 26, 2020 and June 27, 2020 , respectively. We did not recognize an allowance for credit losses against interest receivable in any of the periods presented as there were no such losses. The following table summarizes unrealized losses on our cash equivalents and short-term investments by category and length of time the investment has been in a continuous unrealized loss position as of the periods presented ( in millions ): Less than 12 months Fair Value Unrealized Losses December 26, 2020: U.S. Agency securities $ 36.6 $ — Commercial paper 72.6 — Corporate debt securities 246.1 (0.2) U.S. government bonds 151.8 — Total $ 507.1 $ (0.2) June 27, 2020: Certificates of deposit $ 3.1 $ — Commercial paper 51.1 — Corporate debt securities 96.5 (0.1) Foreign government bonds 1.7 — U.S. Agency securities 47.0 — U.S. government bonds 159.8 — Total $ 359.2 $ (0.1) As of December 26, 2020 and June 27, 2020 , we have no unrealized loss positions for a period of greater than 12 months on our cash equivalents and short-term investments. The following table classifies our short-term investments by contractual maturities ( in millions ): December 26, 2020 June 27, 2020 Amortized Cost Fair Value Amortized Cost Fair Value Due in 1 year $ 1,036.5 $ 1,036.9 $ 1,237.4 $ 1,239.9 Due in 1 year through 5 years 342.0 342.1 15.5 15.9 $ 1,378.5 $ 1,379.0 $ 1,252.9 $ 1,255.8 All available-for-sale securities have been classified as current, based on management’s intent and ability to use the funds in current operations.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Dec. 26, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 5. Fair Value Measurements We determine fair value based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value assumes that the transaction to sell the asset or transfer the liability occurs in the principal or most advantageous market for the asset or liability and establishes that the fair value of an asset or liability shall be determined based on the assumptions that market participants would use in pricing the asset or liability. The classification of a financial asset or liability within the hierarchy is based upon the lowest level input that is significant to the fair value measurement. The fair value hierarchy prioritizes the inputs into three levels that may be used to measure fair value: Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2: Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3: Inputs are unobservable inputs based on our assumptions. The fair value of our Level 1 financial instruments, such as money market funds and U.S. Treasury securities, which are traded in active markets, is based on quoted market prices for identical instruments. The fair value of our Level 2 fixed income securities is obtained from an independent pricing service, which may use quoted market prices for identical or comparable instruments or model driven valuations using observable market data or inputs corroborated by observable market data. Our marketable securities are held by custodians who obtain investment prices from a third-party pricing provider that incorporates standard inputs in various asset price models. Our procedures include controls to ensure that appropriate fair values are recorded, including comparing the fair values obtained from our pricing service against fair values obtained from another independent source. Financial assets measured at fair value on a recurring basis are summarized below ( in millions ): Level 1 Level 2 Level 3 Total December 26, 2020: (1) Assets: Cash equivalents: Commercial paper $ — $ 10.0 $ — $ 10.0 Money market funds 203.6 — — 203.6 Short-term investments: Certificates of deposit — 4.9 — 4.9 Commercial paper — 112.8 — 112.8 Corporate debt securities — 523.5 — 523.5 U.S. Agency securities — 60.6 — 60.6 U.S. Treasury securities 677.2 — — 677.2 Total assets $ 880.8 $ 711.8 $ — $ 1,592.6 (1) Excludes $107.7 million in cash held in our bank accounts at December 26, 2020. Level 1 Level 2 Level 3 Total June 27, 2020: (1) Assets: Cash equivalents: Money market funds $ 159.6 $ — $ — $ 159.6 U.S. Treasury securities 24.2 — — 24.2 Short-term investments: Certificates of deposit — 12.9 — 12.9 Commercial paper — 180.2 — 180.2 Corporate debt securities — 436.6 — 436.6 Foreign government bonds — 1.7 — 1.7 U.S. Agency securities — 59.5 — 59.5 U.S. Treasury securities 564.9 — — 564.9 Total assets $ 748.7 $ 690.9 $ — $ 1,439.6 (1) Excludes $114.2 million in cash held in our bank accounts as of June 27, 2020. Financial Instruments Not Recorded at Fair Value on a Recurring Basis We report our financial instruments at fair value with the exception of the 2026 Notes and the 2024 Notes. The estimated fair value of the notes was determined based on the trading price of the notes as of the last day of trading for the period. We consider the fair value of the notes to be a Level 2 measurement as they are not actively traded in markets. The carrying amounts and estimated fair values of the 2026 Notes and the 2024 Notes are as follows for the periods presented ( in millions ): December 26, 2020 June 27, 2020 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value 2026 Notes $ 769.1 $ 1,312.5 $ 749.7 $ 1,070.2 2024 Notes 380.3 765.1 370.6 620.0 $ 1,149.4 $ 2,077.6 $ 1,120.3 $ 1,690.2 Assets Measured at Fair Value on a Non-Recurring Basis We periodically review our intangible and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Determination of recoverability is based on the lowest level of identifiable estimated undiscounted cash flows resulting from use of the asset and its eventual disposition. If not recoverable, an impairment loss would be calculated based on the excess of the carrying amount over the fair value. Management utilizes various valuation methods, including an income approach, a market approach and a cost approach, to estimate the fair value of intangibles and other long-lived assets. During the annual impairment testing performed in the fourth quarter of fiscal 2020, we concluded that our intangible and other long-lived assets were not impaired. We review our intangible and other long-lived assets for impairment at least annually in the fourth quarter of each fiscal year, absent any interim indicators of impairment.

Balance Sheet Details

Balance Sheet Details	6 Months Ended
	Dec. 26, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Details	Note 6. Balance Sheet Details Allowance for current expected credit losses We did not have any allowance for credit losses other than our allowance for uncollectible accounts receivable. As of December 26, 2020 and June 27, 2020, the allowance for credit losses on our trade receivables was $1.7 million and $1.8 million, respectively. Inventories The components of inventories were as follows ( in millions ): December 26, 2020 June 27, 2020 Raw materials and purchased parts $ 70.4 $ 57.9 Work in process 84.2 67.6 Finished goods 52.5 63.4 Inventories $ 207.1 $ 188.9 Operating lease right-of-use assets, net Operating lease right-of-use assets, net were as follows ( in millions ): December 26, 2020 June 27, 2020 Operating lease right-of-use assets $ 88.7 $ 90.3 Less: accumulated amortization (16.9) (11.6) Operating lease right-of-use assets, net $ 71.8 $ 78.7 Property, plant and equipment, net The components of property, plant and equipment, net were as follows ( in millions ): December 26, 2020 June 27, 2020 Land $ 44.1 $ 44.1 Buildings and improvement 118.1 114.8 Machinery and equipment 517.2 487.0 Computer equipment and software 28.7 27.5 Furniture and fixtures 8.6 7.2 Leasehold improvements 29.5 27.8 Finance lease right-of-use assets 28.1 28.1 Construction in progress 45.6 54.7 819.9 791.2 Less: Accumulated depreciation (434.1) (398.2) Property, plant and equipment, net $ 385.8 $ 393.0 During the three and six months ended December 26, 2020, we recorded depreciation expense of $23.8 million and $47.6 million, respectively. During the three and six months ended December 28, 2019, we recorded depreciation expense of $28.7 million and $60.3 million, respectively. Our construction in progress primarily includes machinery and equipment that we expect to place in service in the next 12 months. Other current liabilities The components of other current liabilities were as follows (in millions) : December 26, 2020 June 27, 2020 Restructuring accrual and related charges (1) $ 4.6 $ 5.2 Warranty accrual (2) 5.7 5.0 Deferred revenue and customer deposits 0.5 1.9 Finance lease liabilities, current 0.3 0.6 Income tax payable (3) 51.5 28.8 Other current liabilities 2.7 2.8 Other current liabilities $ 65.3 $ 44.3 (1) Refer to “Note 11. Restructuring and Related Charges.” (2) Refer to “Note 14. Commitments and Contingencies.” (3) Refer to “Note 12. Income Taxes.” Other non-current liabilities The components of other non-current liabilities were as follows ( in millions ): December 26, 2020 June 27, 2020 Asset retirement obligations $ 4.7 $ 4.6 Pension accrual 12.2 11.8 Unrecognized tax benefit 18.9 17.3 Other non-current liabilities 2.3 2.3 Other non-current liabilities $ 38.1 $ 36.0

Leases

Leases	6 Months Ended
	Dec. 26, 2020
Leases [Abstract]
Leases	Note 7. Leases We lease certain real and personal property from unrelated third parties under non-cancellable operating leases that expire at various dates through fiscal 2033. These operating leases are mainly for administrative offices, research-and-development and manufacturing facilities, as well as sales offices in various countries around the world. Certain leases require us to pay property taxes, insurance and routine maintenance, and include escalation clauses. Many leases include one or more options to renew. We do not assume renewals in our determination of the lease term unless the renewals are deemed to be reasonably assured at lease commencement. We also have various finance leases of servers and certain other equipment for our operations. These arrangements are typically for two As of December 26, 2020, we sublease certai n floors of our offices in the United Kingdom, the United States, Canada, and Japan. These subleases will expire at various dates by fiscal year 2023. We anticipate receiving approximately $4.4 million in sublease income over the next two years. The components of lease costs, lease term, and discount rate are as follows: Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Finance lease cost ( in millions ): Amortization of right-of-use assets $ 0.1 $ 4.3 $ 0.3 $ 8.2 Interest — — — 0.1 Operating lease cost 3.6 4.0 7.2 8.0 Short-term and variable lease costs 1.2 1.0 2.3 2.1 Sublease income (0.7) (0.6) (1.4) (1.2) Total lease cost $ 4.2 $ 8.7 $ 8.4 $ 17.2 December 26, 2020 June 27, 2020 Weighted average remaining lease term ( in years ): Operating leases 8.0 8.6 Finance leases 0.5 1.0 Weighted average discount rate: Operating leases 3.5 % 3.5 % Finance leases 4.4 % 4.4 % As of December 26, 2020, maturities of our operating and finance lease liabilities, which do not include short-term leases and variable lease payments, were as follows ( in millions ): Fiscal Years Operating Leases (1) Finance Leases Total Remainder of 2021 $ 6.8 $ 0.3 $ 7.1 2022 13.1 — 13.1 2023 11.8 — 11.8 2024 10.1 — 10.1 2025 6.7 — 6.7 Thereafter 26.3 — 26.3 Total minimum lease payments $ 74.8 $ 0.3 $ 75.1 Less: amount representing interest (8.9) — (8.9) Present value of total lease liabilities $ 65.9 $ 0.3 $ 66.2 (1) Non-cancellable sublease proceeds for the remainder of fi scal 2021, and fiscal 2022, and 2023 of $1.5 million, $2.3 million, and $0.6 million, respectively, are not included in the table above.
Leases	Note 7. Leases We lease certain real and personal property from unrelated third parties under non-cancellable operating leases that expire at various dates through fiscal 2033. These operating leases are mainly for administrative offices, research-and-development and manufacturing facilities, as well as sales offices in various countries around the world. Certain leases require us to pay property taxes, insurance and routine maintenance, and include escalation clauses. Many leases include one or more options to renew. We do not assume renewals in our determination of the lease term unless the renewals are deemed to be reasonably assured at lease commencement. We also have various finance leases of servers and certain other equipment for our operations. These arrangements are typically for two As of December 26, 2020, we sublease certai n floors of our offices in the United Kingdom, the United States, Canada, and Japan. These subleases will expire at various dates by fiscal year 2023. We anticipate receiving approximately $4.4 million in sublease income over the next two years. The components of lease costs, lease term, and discount rate are as follows: Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Finance lease cost ( in millions ): Amortization of right-of-use assets $ 0.1 $ 4.3 $ 0.3 $ 8.2 Interest — — — 0.1 Operating lease cost 3.6 4.0 7.2 8.0 Short-term and variable lease costs 1.2 1.0 2.3 2.1 Sublease income (0.7) (0.6) (1.4) (1.2) Total lease cost $ 4.2 $ 8.7 $ 8.4 $ 17.2 December 26, 2020 June 27, 2020 Weighted average remaining lease term ( in years ): Operating leases 8.0 8.6 Finance leases 0.5 1.0 Weighted average discount rate: Operating leases 3.5 % 3.5 % Finance leases 4.4 % 4.4 % As of December 26, 2020, maturities of our operating and finance lease liabilities, which do not include short-term leases and variable lease payments, were as follows ( in millions ): Fiscal Years Operating Leases (1) Finance Leases Total Remainder of 2021 $ 6.8 $ 0.3 $ 7.1 2022 13.1 — 13.1 2023 11.8 — 11.8 2024 10.1 — 10.1 2025 6.7 — 6.7 Thereafter 26.3 — 26.3 Total minimum lease payments $ 74.8 $ 0.3 $ 75.1 Less: amount representing interest (8.9) — (8.9) Present value of total lease liabilities $ 65.9 $ 0.3 $ 66.2 (1) Non-cancellable sublease proceeds for the remainder of fi scal 2021, and fiscal 2022, and 2023 of $1.5 million, $2.3 million, and $0.6 million, respectively, are not included in the table above.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	6 Months Ended
	Dec. 26, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Note 8. Goodwill and Other Intangible Assets Goodwill The following table presents our goodwill balance by the reportable segments as of December 26, 2020 and June 27, 2020 ( in millions) : Optical Communications Commercial Lasers Total Balance as of December 26, 2020 and June 27, 2020 $ 363.5 $ 5.4 $ 368.9 Impairment of Goodwill We review goodwill for impairment during the fourth quarter of each fiscal year or more frequently if events or circumstances indicate that an impairment loss may have occurred. In the fourth quarter of fiscal 2020, we completed the annual impairment test of goodwill, which indicated there was no goodwill impairment. There were no indicators of goodwill impairment during the three and six months ended December 26, 2020. Other Intangibles The intangible assets are amortized on a straight-line basis over the estimated useful lives, except for customer relationships and order backlog, which are amortized using an accelerated method of amortization over the expected customer lives, which more accurately reflects the pattern of realization of economic benefits expected to be obtained. Acquired developed technologies and order backlog are amortized to cost of sales and customer relationships is amortized to selling, general and administrative. IPR&D is initially capitalized at fair value as an intangible asset with an indefinite life and assessed for impairment thereafter. When an IPR&D project is completed, the IPR&D is reclassified as an amortizable purchased intangible asset and amortized over the asset’s estimated useful life expected to range between 4 to 9 years. On October 29, 2020, we purchased intellectual property from the third party for a total consideration of $10.0 million. These intangible assets have an estimated useful life of 5 years. The following tables present details of our other intangibles as of the periods presented ( in millions, except for weighted average remaining amortization period ): December 26, 2020 Gross Carrying Amounts Accumulated Amortization Net Carrying Amounts Weighted average remaining amortization period (years) Acquired developed technologies $ 381.5 $ (207.2) $ 174.3 3.4 Customer relationships 149.3 (48.4) 100.9 6.0 In-process research and development 10.0 — 10.0 n/a Order backlog 22.0 (22.0) — — Other intangibles 2.7 (2.7) — — Total intangible assets $ 565.5 $ (280.3) $ 285.2 June 27, 2020 Gross Carrying Amounts Accumulated Amortization Net Carrying Amounts Weighted average remaining amortization period (years) Acquired developed technologies $ 371.5 $ (176.9) $ 194.6 3.7 Customer relationships 149.3 (37.1) 112.2 6.5 In-process research and development 10.0 — 10.0 n/a Order backlog 22.0 (22.0) — — Other intangibles 2.7 (2.7) — — Total intangible assets $ 555.5 $ (238.7) $ 316.8 The following table presents details of amortization for the periods presented (in millions ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Cost of sales $ 15.0 $ 12.4 $ 30.0 $ 24.9 Selling, general and administrative 5.9 6.2 11.6 12.5 Total amortization of intangibles $ 20.9 $ 18.6 $ 41.6 $ 37.4 Based on the carrying amount of our acquired developed technologies and other intangibles, excluding IPR&D, as of December 26, 2020, and assuming no future impairment of the underlying assets, the estimated future amortization is as follows (in millions) : Fiscal Years Remainder of 2021 $ 42.3 2022 82.1 2023 58.6 2024 38.8 2025 27.7 Thereafter 25.7 Total future amortization $ 275.2

Debt

Debt	6 Months Ended
	Dec. 26, 2020
Debt Disclosure [Abstract]
Debt	Note 9. Debt Convertible Notes 2026 Notes In December 2019, we issued $1,050.0 million in aggregate principal amount of the 2026 Notes in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The 2026 Notes are governed by an indenture between the Company and U.S. Bank National Association (the “2026 Indenture”). We used approximately $196 million of the net proceeds of the offering to repay in full all amounts outstanding under our term loan credit facility, and a portion of the net proceeds of the offering to purchase approximately $200 million of our common stock concurrently with the pricing of the offering in privately negotiated transactions. The 2026 Notes are unsecured and do not contain any financial covenants, restrictions on dividends, incurrence of senior debt or other indebtedness, or the issuance or repurchase of securities by us. The 2026 Notes wil l bear interest at a rate of 0.50% per year, payable semi-annually in arrears on June 15 and December 15 of each year, beginning on June 15, 2020. The 2026 Notes will mature on December 15, 2026, unless earlier redeemed, repurchased by us, or converted pursuant to their terms. The initial conversion rate is 10.0711 shares of common stock per $1,000 principal amount of the 2026 Notes (which is equivalent to an initial conversion price of approximately $99.29 per share). The conversion rate is subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a make-whole fundamental change or our issuance of a notice of redemption, we will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert the 2026 Notes in connection with such make-whole fundamental change or notice of redemption. Prior to the close of business on the business day immediately preceding September 15, 2026, holders of the 2026 Notes may convert their 2026 Notes only under certain circumstances discussed in detail in our Annual Report on Form 10-K for the year ended June 27, 2020. 2024 Notes In March 2017, we issued $450.0 million of the 2024 Notes in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act. The 2024 Notes are governed by an indenture between the Company, as the issuer, and U.S. Bank National Association, as trustee (the “2024 Indenture”). The 2024 Notes are unsecured and do not contain any financial covenants, restrictions on dividends, incurrence of senior debt or other indebtedness, or the issuance or repurchase of securities by us. The 2024 Notes bear interest at a rate of 0.25% per year. Interest on the 2024 Notes is payable semi-annually in arrears on March 15 and September 15 of each year, beginning on September 15, 2017. The 2024 Notes will mature on March 15, 2024, unless earlier repurchased by us or converted pursuant to their terms. The initial conversion rate of the 2024 Notes is 16.4965 shares of common stock per $1,000 principal amount of 2024 Notes, which is equivalent to an initial conversion price of approximately $60.62 per share, a 132.5% premium to the fair market value at the date of issuance. Prior to the close of business on the business day immediately preceding December 15, 2023, each holder of the 2024 Notes may convert their 2024 Notes only under certain circumstances discussed in detail in our Annual Report on Form 10-K for the year ended June 27, 2020. Our convertible notes consisted of the following components as of the periods presented ( in millions ): Liability component: December 26, 2020 June 27, 2020 2024 Notes (1) 2026 Notes 2024 Notes (1) 2026 Notes Principal $ 450.0 $ 1,050.0 $ 450.0 $ 1,050.0 Unamortized debt discount and debt issuance costs (69.7) (280.9) (79.4) (300.3) Net carrying amount of the liability component $ 380.3 $ 769.1 $ 370.6 $ 749.7 (1) Since the closing price of our stock exceeded $78.80 (or 130% of the conversion price of $60.62 ) for 20 of the last 30 trading days of the second quarter of fiscal 2021, the 2024 Notes have become convertible at the option of the holders. Therefore, the debt component of our 2024 Notes as of December 26, 2020 was reclassified to current liabilities in our condensed consolidated balance sheet. If the closing price of our stock exceeds $129.08 (or 130% of the conversion price of $99.29) for 20 of the last 30 trading days of any future quarter, our 2026 Notes would also become convertible at the option of the holders and the debt component would be reclassified to current liabilities in our condensed consolidated balance sheet. The following table sets forth interest expense information related to the convertible notes for the periods presented (in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Contractual interest expense $ 1.6 $ 0.5 $ 3.2 $ 0.7 Amortization of the debt discount and debt issuance costs 14.7 6.2 29.1 10.8 Total interest expense $ 16.3 $ 6.7 $ 32.3 $ 11.5 The future interest and principal payments related to our convertible notes are as follows as of December 26, 2020 (in millions) : Fiscal Years 2024 Notes 2026 Notes Total Remainder of 2021 $ 0.6 $ 2.6 $ 3.2 2022 1.1 5.3 6.4 2023 1.1 5.3 6.4 2024 451.1 5.3 456.4 2025 — 5.3 5.3 Thereafter — 1,057.7 1,057.7 Total convertible notes payments $ 453.9 $ 1,081.5 $ 1,535.4 The principal balances of our Notes are reflected in the payment periods in the table above based on their respective contractual maturities assuming no conversion. Term Loan Facility In December 2018, concurrent with the closing of the Oclaro merger, we entered into a credit agreement providing for a term loan facility (the “Term Loan Facility”) in an aggregate principal amount of $500.0 million and we drew in full the term loans available under the Term Loan Facility on the closing date of the Oclaro merger. In the second quarter of fiscal 2020, we repaid, in full, all amounts outstanding under our Term Loan Facility. During the three and six months ended December 28, 2019 , we incurred $11.6 million and $18.1 million of interest expense on this Term Loan Facility, which includes $8.0 million loss on early extinguishment of debt for each period, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Dec. 26, 2020
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Note 10. Accumulated Other Comprehensive Income (Loss) Our accumulated other comprehensive income (loss) consists of the accumulated net unrealized gains or losses on foreign currency translation adjustments, the defined benefit obligations, and available-for-sale securities. The changes in accumulated other comprehensive income (loss) were as follows for the periods as presented ( in millions ): Foreign currency translation adjustments, net of tax (1) Defined benefit obligations, net of tax (2) Unrealized gain (loss) on available-for-sale securities, net of tax Total Beginning balance as of June 27, 2020 $ 9.7 $ (4.2) $ 2.4 $ 7.9 Other comprehensive loss — — (1.5) (1.5) Ending balance as of September 26, 2020 9.7 (4.2) 0.9 6.4 Other comprehensive loss (3) — — (0.4) (0.4) Ending balance as of December 26, 2020 $ 9.7 $ (4.2) $ 0.5 $ 6.0 Beginning balance as of June 29, 2019 $ 9.7 $ (3.5) $ 0.9 $ 7.1 Other comprehensive income — — 0.1 0.1 Ending balance as of September 28, 2019 9.7 (3.5) 1.0 7.2 Other comprehensive loss — — (0.2) (0.2) Ending balance as of December 28, 2019 $ 9.7 $ (3.5) $ 0.8 $ 7.0 (1) In fiscal 2019, as a result of significant changes in economic facts and circumstances, primarily due to the acquisition of Oclaro, we established the functional currency for our worldwide operations as the U.S. dollar. Translation adjustments reported prior to December 10, 2018, remain as a component of accumulated other comprehensive income in our condensed consolidated balance sheets, until all or a part of the investment in the subsidiaries is sold or liquidated. (2) We evaluate the assumptions over the fair value of our defined benefit obligations annually and make changes as necessary.

Restructuring and Related Charg

Restructuring and Related Charges	6 Months Ended
	Dec. 26, 2020
Restructuring and Related Activities [Abstract]
Restructuring and Related Charges	Note 11. Restructuring and Related Charges In previous years we have initiated various strategic restructuring actions primarily intended to reduce costs, consolidate our operations, rationalize the manufacturing of our products and align our business in response to market conditions. The following table summarizes the activity of restructuring and related charges during the three and six months ended December 26, 2020 and December 28, 2019 ( in millions ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Balance as of beginning of period $ 4.4 $ 10.7 $ 5.2 $ 14.6 Charges 0.2 0.9 0.2 2.2 Payments — (6.6) (0.8) (11.8) Balance as of end of period $ 4.6 $ 5.0 $ 4.6 $ 5.0 During the three and six months ended December 26, 2020, we recorded restructuring and related charges of $0.2 million for both periods in our condensed consolidated statements of operations. The payments of $0.8 million during the six months ended December 26, 2020 were mainly attributable to previously recognized severance charges associated with the decision to move certain manufacturing from San Jose, California to our facility in Thailand and other third party vendors. During the three and six months ended December 28, 2019, we recorded $0.9 million and $2.2 million, respectively, in restructuring and related charges in our condensed consolidated statements of operations. The charges were mainly attributable to severance charges associated with ongoing acquisition related synergies. Any changes in the estimates of executing our restructuring activities will be reflected in our future results of operations.

Income Taxes

Income Taxes	6 Months Ended
	Dec. 26, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 12. Income Taxes Our tax provision for interim periods is determined using an estimate of our annual effective tax rate, adjusted for discrete items, if any, that arise during the period. Each quarter, we update our estimate of the annual effective tax rate, and if the estimated annual effective tax rate changes, we make a cumulative adjustment in such period. Our quarterly tax provision and estimate of our annual effective tax rate are subject to variation due to several factors, including variability in pre-tax income (or loss), the mix of jurisdictions to which such income relates, changes in how we do business, and tax law developments. We recorded a tax provision of $14.9 million and $31.4 million for the three and six months ended December 26, 2020, respectively. Our tax provision for the three months ended December 26, 2020 includes a discrete tax benefit of $2.5 million mainly from the reversal of certain deferred tax liabilities recorded in prior periods and the excess benefit related to certain stoc k-based compensation that vested during the quarter, partially offset by currency re-measurement of certain tax related accounts. Our estimated effective tax rate for fiscal 2021 differs from the 21% U.S. statutory rate primarily due to the earnings of our foreign subsidiaries being taxed at rates that differ from the U.S. statutory rate as well as the U.S. federal R&D tax credits, partially offset by the income tax expense from non-deductible stock-based compensation and the tax effect of Global Intangible Low-Taxed Income (“GILTI”), net of a benefit for foreign tax credits, Base Erosion and Anti-Abuse Tax (“BEAT”), and subpart F inclusion. As of December 26, 2020, we had $27.6 million of unrecognized tax benefits, which, if recognized, would affect the effective tax rate. We are subject to examination of income tax returns by various domestic and foreign tax authorities. The timing of commencement, resolution and closure of tax audits is highly unpredictable. Although it is possible that certain ongoing tax audits may be concluded within the next 12 months, we cannot reasonably estimate the impact to tax expense and net income from tax exams that could be resolved or closed within the next 12 months. Subject to audit timing and uncertainty, we expect our unrecognized tax benefit amount that could affect the effective tax rate to decrease by $5.3 million over the next 12 months. We believe that we have adequately provided under GAAP for potential outcomes related to our tax audits. However, there can be no assurances as to the possible outcomes or any related financial statement effect thereof.

Equity

Equity	6 Months Ended
	Dec. 26, 2020
Equity [Abstract]
Equity	Note 13. Equity Description of Lumentum Stock-Based Benefit Plans Equity Incentive Plan As of December 26, 2020, we had 2.3 million shares subject to restricted stock units and performance stock units issued and outstanding under the 2015 Equity Incentive Plan (the “2015 Plan”). Restricted stock units and performance stock units are performance-based, time-based or a combination of both. The fair value of these grants is based on the closing market price of our common stock on the date of award. As of December 26, 2020, 2.3 million shares of common stock under the 2015 Plan were available for grant. Replacement Awards In connection with the acquisition of Oclaro, we issued equity awards to Oclaro employees (“replacement awards”) in exchange for their Oclaro equity awards. As of December 26, 2020, we had 0.2 million of unvested shares subject to restricted stock units under the replacement awards. Restricted Stock Units Restricted stock units (“RSUs”) under the 2015 Plan are grants of shares of our common stock, the vesting of which is based on the requisite service requirement. Generally, our RSUs are subject to forfeiture and are expected to vest over one Performance Stock Units Performance stock units (“PSUs”) under the 2015 Plan are grants of shares of our common stock that vest upon the achievement of certain performance and service conditions. We begin recognizing compensation expense when we conclude that it is probable that the performance conditions will be achieved. We reassess the probability of vesting at each reporting period and adjust our compensation cost based on this probability assessment. Our PSUs are subject to risk of forfeiture until performance and service conditions are satisfied and generally vest over three years. Employee Stock Purchase Plan Our 2015 Employee Stock Purchase Plan (the “2015 Purchase Plan”) provides eligible employees with the opportunity to acquire an ownership interest in the Company through periodic payroll deductions and provides a 15% purchase price discount as well a s a 6-month look-back peri od. The 2015 Purchase Plan is structured as a qualified employee stock purchase plan under Section 423 of the Internal Revenue Code of 1986, as amended. The 2015 Purchase Plan will terminate upon the date on which all shares available for issuance have been sold. Of the 3.0 million shares authorized under the 2015 Purchase Plan, 1.7 million shares remained available for issuance as of December 26, 2020. Stock-Based Compensation The impact on our results of operations of recording stock-based compensation by function for the three and six months ended December 26, 2020 and December 28, 2019 was as follows (in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Cost of sales $ 4.8 $ 4.1 $ 8.5 $ 8.3 Research and development 5.1 4.1 9.5 7.9 Selling, general and administrative 14.2 12.0 25.6 20.7 Total stock-based compensation $ 24.1 $ 20.2 $ 43.6 $ 36.9 Total income tax benefit associated with stock-based compensation recognized in our consolidated statements of operations during the years presented was as follows (in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Income tax benefit associated with stock-based compensation $ 3.6 $ 3.8 $ 8.8 $ 6.6 Approximately $4.9 million and $3.6 million of stock-based compensation was capitalized to inventory as of December 26, 2020 and June 27, 2020, respectively. Stock Award Activity The following table summarizes our awards activity for the six months ended December 26, 2020 (in millions, except per share amounts) : Restricted Stock Units Performance Stock Units Number of Shares Weighted-Average Grant Date Fair Value per Share Number of Shares Weighted-Average Grant Date Fair Value per Share Balance as of June 27, 2020 1.9 $ 56.6 0.3 $ 60.6 Granted 1.1 86.7 0.2 86.7 Vested (0.8) 56.1 (0.1) 57.7 Canceled (0.1) 62.3 — 71.8 Balance as of December 26, 2020 2.1 $ 72.2 0.4 $ 73.3 As of December 26, 2020, $168.0 million of stock-based compensation cost related to awards granted to our employees remains to be amortized. That cost is expected to be recognized over an estimated amortization period of 2.0 years. A summary of awards available for grant is as follows (in millions) : Awards Available for Grant Balance as of June 27, 2020 3.5 Granted (1.3) Canceled 0.1 Balance as of December 26, 2020 2.3 Employee Stock Purchase Plan Activity The 2015 Purchase Plan expense for the three months ended December 26, 2020 and December 28, 2019 was $1.2 million and $0.8 million, respectively. The 2015 Purchase Plan expense for the six months ended December 26, 2020 and December 28, 2019 was $2.3 million and $1.7 million, respectively. The expense related to the 2015 Purchase Plan is recorded on a straight-line basis over the relevant subscription period. During the three and six months ended December 26, 2020, there were 0.1 million

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Dec. 26, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 14. Commitments and Contingencies Purchase Obligations Purchase obligations of $219.8 million as of December 26, 2020, represent legally-binding commitments to purchase inventory and other commitments made in the normal course of business to meet operational requirements. Although open purchase orders are considered enforceable and legally binding, the terms generally allow the option to cancel, reschedule and adjust the requirements based on our business needs prior to the delivery of goods or performance of services. Obligations to purchase inventory and other commitments are generally expected to be fulfilled within one year. We depend on a limited number of contract manufacturers, subcontractors and suppliers for raw materials, packages and standard components. We generally purchase these single or limited source products through standard purchase orders or one- year supply agreements and have no significant long-term guaranteed supply agreements with such vendors. While we seek to maintain a sufficient safety stock of such products and maintain on-going communications with our suppliers to guard against interruptions or cessation of supply, our business and results of operations could be adversely affected by a stoppage or delay of supply, substitution of more expensive or less reliable products, receipt of defective parts or contaminated materials, increases in the price of such supplies, or our inability to obtain reduced pricing from our suppliers in response to competitive pressures. Product Warranties We provide reserves for the estimated costs of product warranties at the time revenue is recognized. We typically offer a twelve month warranty for most of our products. However, in some instances depending upon the product, product components or application of our products by the end customer, our warranties can vary and generally range from six months to five years. We estimate the costs of our warranty obligations on an annualized basis based on our historical experience of known product failure rates, use of materials to repair or replace defective products and service delivery costs incurred in correcting product failures. In addition, from time to time, specific warranty accruals may be made if unforeseen technical problems arise with specific products. We assess the adequacy of our recorded warranty liabilities and adjust the amounts as necessary. The following table presents the changes in our warranty reserve during the three and six months ended December 26, 2020 and December 28, 2019 ( in millions ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Balance as of beginning of period $ 7.6 $ 7.0 $ 5.0 $ 7.5 Provision for warranty 0.2 0.6 4.1 1.8 Utilization of reserve (2.1) (0.8) (3.4) (2.5) Balance as of end of period $ 5.7 $ 6.8 $ 5.7 $ 6.8 Environmental Liabilities Our research and development (“R&D”), manufacturing and distribution operations involve the use of hazardous substances and are regulated under international, federal, state and local laws governing health and safety and the environment. We apply strict standards for protection of the environment and occupational health and safety to sites inside and outside the United States, even if not subject to regulations imposed by foreign governments. We believe that our properties and operations at our facilities comply in all material respects with applicable environmental laws and occupational health and safety laws. However, the risk of environmental liabilities cannot be completely eliminated and there can be no assurance that the application of environmental and health and safety laws will not require us to incur significant expenditures. We are also regulated under a number of international, federal, state and local laws regarding recycling, product packaging and product content requirements. The environmental, product content/disposal and recycling laws are gradually becoming more stringent and may cause us to incur significant expenditures in the future. Legal Proceedings We are subject to a variety of claims and suits that arise from time to time in the ordinary course of our business. While management currently believes that resolving claims against us, individually or in the aggregate, will not have a material adverse impact on our financial position, results of operations or statements of cash flows, these matters are subject to inherent uncertainties and management’s view of these matters may change in the future. We accrue for loss contingencies when it is both probable that we will incur the loss and when we can reasonably estimate the amount of the loss or range of loss. Merger Litigation In connection with our acquisition of Oclaro, seven lawsuits were filed by purported stockholders of Oclaro challenging the proposed merger (the “Merger”). Two of the seven suits were putative class actions filed against Oclaro, its directors, Lumentum, Prota Merger Sub, Inc. and Prota Merger, LLC: Nicholas Neinast v. Oclaro, Inc., et al., No. 3:18-cv-03112-VC, in the United States District Court for the Northern District of California (filed May 24, 2018) (the “Neinast Lawsuit”); and Adam Franchi v. Oclaro, Inc., et al., No. 1:18-cv-00817-GMS, in the United States District Court for the District of Delaware (filed June 9, 2018) (the “Franchi Lawsuit”). Both the Neinstat Lawsuit and the Franchi Lawsuit were voluntarily dismissed with prejudice. The other five suits, styled as Gerald F. Wordehoff v. Oclaro, Inc., et al., No. 5:18-cv-03148-NC (the “Wordehoff Lawsuit”), Walter Ryan v. Oclaro, Inc., et al., No. 3:18-cv-03174-VC (the “Ryan Lawsuit”), Jayme Walker v. Oclaro, Inc., et al., No. 5:18-cv-03203-EJD (the “Walker Lawsuit”), Kevin Garcia v. Oclaro, Inc., et al., No. 5:18-cv-03262-VKD (the “Garcia Lawsuit”), and SaiSravan B. Karri v. Oclaro, Inc., et al., No. 3:18-cv-03435-JD (the “Karri Lawsuit” and, together with the other six lawsuits, the “Lawsuits”), were filed in the United States District Court for the Northern District of California on May 25, 2018, May 29, 2018, May 30, 2018, May 31, 2018, and June 9, 2018, respectively. These five Lawsuits named Oclaro and its directors as defendants only and did not name Lumentum. The Wordehoff, Ryan, Walker, and Garcia Lawsuits have been voluntarily dismissed, and the Wordehoff, Ryan, and Walker dismissals were with prejudice. The Karri Lawsuit has not yet been dismissed. The Ryan Lawsuit was, and the Karri Lawsuit is, a putative class action. The Lawsuits generally alleged, among other things, that Oclaro and its directors violated Section 14(a) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and Rule 14a-9 promulgated thereunder by disseminating an incomplete and misleading Form S-4, including proxy statement/prospectus. The Lawsuits further alleged that Oclaro’s directors violated Section 20(a) of the Exchange Act by failing to exercise proper control over the person(s) who violated Section 14(a) of the Exchange Act. The remaining Lawsuit (the Karri Lawsuit) currently purports to seek, among other things, damages to be awarded to the plaintiff and any class, if a class is certified, and litigation costs, including attorneys’ fees. A lead plaintiff and counsel has been selected, and an amended complaint was filed on April 15, 2019, which also names Lumentum as a defendant. A motion to dismiss the amended complaint was granted in part and denied in part by the court on October 8, 2020. On December 1, 2020, defendants answered the amended complaint. On December 23, 2020, defendants filed a motion for leave to file a motion for reconsideration of the Court’s October 8 order on the motion to dismiss, which was denied on January 29, 2021. The Karri Lawsuit remains pending with the parties currently in discovery. Defendants intend to defend the Karri Lawsuit vigorously. Indemnifications In the normal course of business, we enter into agreements that contain a variety of representations and warranties and provide for general indemnification. Exposure under these agreements is unknown because claims may be made against us in the future and we may record charges in the future as a result of these indemnification obligations. As of December 26, 2020, we did not have any material indemnification claims that were probable or reasonably possible. Audit Proceedings We are under audit by various domestic and foreign tax authorities with regards to income tax and indirect tax matters. In some, although not all cases, we have reserved for potential adjustments to our provision for income taxes and accrual of indirect taxes that may result from examinations by these tax authorities or final outcomes in judicial proceedings, and we believe that the final outcome of these examinations, agreements or judicial proceedings will not have a material effect on our results of operations. If events occur which indicate payment of these amounts is unnecessary, the reversal of the liabilities would result in the recognition of benefits in the period we determine the liabilities are no longer necessary. If our estimates of the federal, state, and foreign income tax liabilities and indirect tax liabilities are less than the ultimate assessment, it could result in a further charge to expense.

Operating Segments and Geograph

Operating Segments and Geographic Information	6 Months Ended
	Dec. 26, 2020
Segment Reporting [Abstract]
Operating Segments and Geographic Information	Note 15. Operating Segments and Geographic Information Our chief executive officer is our Chief Operating Decision Maker (“CODM”). The CODM allocates resources to the segments based on their business prospects, competitive factors, net revenue and gross margin. We do not track all of our property, plant and equipment by operating segments. The geographic identification of these assets is set forth below. We are an industry leading provider of optical and photonic products defined by revenue and market share addressing a range of end-market applications including optical communications and commercial lasers. We have two operating segments, Optical Communications, which we refer to as OpComms, and Commercial Lasers, which we refer to as Lasers. Our OpComms products address the following markets: telecommunications and data communications (“Telecom and Datacom”), and consumer and industrial (“Consumer and Industrial”), and include product lines from the acquisition of Oclaro. The two operating segments were primarily determined based on how the CODM views and evaluates our operations. Operating results are regularly reviewed by the CODM to make decisions about resources to be allocated to the segments and to assess their performance. Other factors, including market separation and customer specific applications, go-to-market channels, products and manufacturing, are considered in determining the formation of these operating segments. OpComms Our OpComms products include a wide range of components, modules and subsystems to support customers including carrier networks for access (local), metro (intracity), long-haul (city-to-city and worldwide) and submarine (undersea) applications. Additionally, our products address enterprise, cloud, and data center applications, including storage-access networks (“SANs”), local-area networks (“LANs”) and wide-area networks (“WANs”). These products enable the transmission and transport of video, audio and data over high-capacity fiber-optic cables. We maintain leading positions in these fast growing OpComms markets through our extensive product portfolio, including reconfigurable optical add/drop multiplexers (“ROADMs”), coherent dense wavelength division multiplexing (“DWDM”) pluggable transceivers, and tunable small form-factor pluggable transceivers. We also sell laser chips for use in the manufacture of high-speed Datacom transceivers. In the Consumer and Industrial market, our OpComms diode laser products include vertical cavity surface emitting lasers (“VCSELs”) and edge emitting lasers. In the Consumer end-market, our laser light sources are integrated into 3D sensing cameras which are used in applications in mobile devices, gaming, payment kiosks, computers, and other consumer electronics devices. Applications include biometric identification, computational photography, virtual and augmented reality, and natural user interfaces. Emerging applications for our lasers include automotive safety systems, LiDAR for advanced driver assistance systems in automobiles and autonomous vehicles, self-navigating robotics and drones in industrial applications, and 3D capture of objects coupled with 3D imaging or printing. In the Industrial end-market, our diode lasers are used primarily as pump sources for pulsed and kilowatt class fiber lasers. Lasers Our Lasers products serve our customers in markets and applications such as sheet metal processing, general manufacturing, biotechnology, graphics and imaging, remote sensing, and precision machining such as drilling in printed circuit boards, wafer singulation, glass cutting and solar cell scribing. Our Lasers products are used in a variety of OEM applications including diode-pumped solid-state, fiber, diode, direct-diode and gas lasers such as argon-ion and helium-neon lasers. Fiber lasers provide kW-class output powers combined with excellent beam quality and are used in sheet metal processing and metal welding applications. Diode-pumped solid-state lasers provide excellent beam quality, low noise and exceptional reliability and are used in biotechnology, graphics and imaging, remote sensing, materials processing and precision machining applications. Diode and direct-diode lasers address a wide variety of applications, including laser pumping, thermal exposure, illumination, ophthalmology, image recording, printing, plastic welding and selective soldering. Gas lasers such as argon-ion and helium-neon lasers provide a stable, low-cost and reliable solution over a wide range of operating conditions, making them well-suited for complex, high-resolution OEM applications such as flow cytometry, DNA sequencing, graphics and imaging and semiconductor inspection. We also provide high-powered and ultrafast lasers for the industrial and scientific markets. Manufacturers use high-power, ultrafast lasers to create micro parts for consumer electronics and to process semiconductor, LED, and other types of chips. Use of ultrafast lasers for micromachining applications is being driven primarily by the increasing use of consumer electronics and connected devices globally. We do not allocate research and development, sales and marketing, or general and administrative expenses to our segments because management does not include the information in its measurement of the performance of the operating segments. In addition, we do not allocate amortization and impairment of acquisition-related intangible assets, stock-based compensation and certain other charges impacting the gross margin of each segment because management does not include this information in its measurement of the performance of the operating segments. Information on reportable segments utilized by our CODM is as follows ( in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Net revenue: OpComms $ 449.1 $ 409.4 $ 877.6 $ 825.5 Lasers 29.7 48.4 53.6 82.2 Net revenue $ 478.8 $ 457.8 $ 931.2 $ 907.7 Gross profit: OpComms $ 241.8 $ 196.4 $ 466.6 $ 388.3 Lasers 14.1 20.4 24.5 34.6 Total segment gross profit 255.9 216.8 491.1 422.9 Unallocated corporate items: Stock-based compensation (4.8) (4.1) (8.5) (8.3) Amortization of acquired intangibles (15.0) (12.4) (30.0) (24.9) Amortization of inventory fair value adjustments — (2.1) — (4.3) Inventory and fixed asset write down due to product line exits (0.1) (2.6) (0.4) (3.7) Integration related costs — — — (3.4) Other charges (1) (6.4) (6.5) (16.9) (21.5) Gross profit $ 229.6 $ 189.1 $ 435.3 $ 356.8 (1) “Other charges” of unallocated corporate items for the three and six months ended December 26, 2020 include costs of transferring product lines to new production facilities, including Thailand of $0.4 million and $2.5 million, respectively. We also incurred excess and obsolete inventory charges driven by U.S. trade restrictions and the related decline in demand from Hua wei of $0.8 million and $6.7 million during the three and six months ended December 26, 2020, respectively. In addition, during the three months ended December 26, 2020, we incurred $4.6 million of impairment charges associ ated with excess capacity related to our Fiber laser business. “Other charges” of unallocated corporate items for the three and six months ended December 28, 2019 include costs of transferring product lines to new production facilities, including Thailand of $2.0 million and $8.1 million, respectively. We also incurred excess and obsolete inventory charges driven by the decline in demand from Huawei of $6.0 million and $12.7 million during the three and six months ended December 28, 2019. Disaggregation of Revenue We disaggregate revenue by product and by geography. We do not present other levels of disaggregation, such as by type of products, customer, markets, contracts, duration of contracts, timing of transfer of control and sales channels, as this information is not used by our CODM to manage the business. The table below discloses our total net revenue attributable to each of our two reportable segments. In addition, the table sets forth the percentage of our total net revenue attributable to our product offerings which serve Telecom and Datacom, and Consumer and Industrial markets which accounted for 10% or more of our total net revenue during the periods presented ( in millions, except percentage data ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 OpComms: Telecom and Datacom $ 286.2 59.8 % $ 266.3 58.2 % $ 547.5 58.8 % $ 514.4 56.6 % Consumer and Industrial 162.9 34.0 143.1 31.2 330.1 35.4 311.1 34.3 Total OpComms $ 449.1 93.8 % $ 409.4 89.4 % $ 877.6 94.2 % $ 825.5 90.9 % Lasers 29.7 6.2 48.4 10.6 53.6 5.8 82.2 9.1 Total Revenue $ 478.8 $ 457.8 $ 931.2 $ 907.7 We operate in three geographic regions: Americas, Asia-Pacific, and EMEA (Europe, Middle East, and Africa). Net revenue is assigned to the geographic region and country where our product is initially shipped. For example, certain customers may request shipment of our product to a contract manufacturer in one country, which may differ from the location of their end customers. The following table presents net revenue by the three geographic regions we operate in and net revenue from countries that represented 10% or more of our total net revenue (in millions, except percentage data): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Net revenue: Amount % of Total Amount % of Total Amount % of Total Amount % of Total Americas: United States $ 39.7 8.3 % $ 43.4 9.5 % $ 60.0 6.4 % $ 80.3 8.8 % Mexico 51.3 10.7 26.2 5.7 91.1 9.8 55.1 6.1 Other Americas 4.0 0.8 0.7 0.2 6.8 0.8 1.8 0.2 Total Americas $ 95.0 19.8 % $ 70.3 15.4 % $ 157.9 17.0 % $ 137.2 15.1 % Asia-Pacific: Hong Kong $ 148.0 30.9 % $ 144.5 31.6 % $ 292.4 31.4 % $ 278.3 30.7 % Philippines 40.6 8.5 4.8 1.0 103.4 11.1 29.8 3.3 South Korea 66.0 13.8 85.0 18.6 122.0 13.1 176.6 19.5 Other Asia-Pacific 94.0 19.6 116.1 25.4 185.6 19.9 216.4 23.8 Total Asia-Pacific $ 348.6 72.8 % $ 350.4 76.6 % $ 703.4 75.5 % $ 701.1 77.3 % EMEA $ 35.2 7.4 % $ 37.1 8.0 % $ 69.9 7.5 % $ 69.4 7.6 % Total net revenue $ 478.8 $ 457.8 $ 931.2 $ 907.7 During the three and six months ended December 26, 2020 compared to the three and six months ended December 28, 2019, our net revenue from the Philippines grew due to an introduction of a new product to one of our large customers. Transaction Price Allocated to the Remaining Performance Obligations The following table includes estimated revenue expected to be recognized in the future for backlog related performance obligations that are unsatisfied as of December 26, 2020 ( in millions ): Less than 1 year 1-2 years Greater than 2 years Total Performance obligations $475.4 $2.4 $— $477.8 Contract Balances The following table reflects the changes in contract balances as of December 26, 2020 ( in millions, except percentages ): Contract balances Balance sheet location December 26, 2020 June 27, 2020 Change Percentage Change Accounts receivable, net Accounts receivable, net $276.7 $233.5 $43.2 18.5% Deferred revenue and customer deposits Other current liabilities $0.5 $1.9 $(1.4) (73.7)% During the three and six months ended December 26, 2020, our net revenue from a single customer, which represented 10% or greater of total net revenue was concentrated with two customers, who collectively accounted for 45% of our total net revenue for each period, respectively. During the three and six months ended December 28, 2019, our net revenue from a single customer, which represented 10% or greater of total net revenue was concentrated with two customers, who collectively accounted for 41% and 44% of our total net revenue, respectively. As of December 26, 2020, our accounts receivable balance was concentrated with two cus tomers, which individually represented 10% or greater of gross accounts receivable and collectively accounted f or 24% o f the balance. As of June 27, 2020, one customer represented 10% or greater of gross accounts receivable and accounted for 14% of the balance. Long-lived assets, namely net property, plant and equipment, net, were identified based on the physical location of the assets in the corresponding geographic areas as of the periods indicated (in millions) : December 26, 2020 June 27, 2020 Property, plant and equipment, net United States $ 138.6 $ 139.1 Thailand 112.1 122.6 China 42.5 43.2 Japan 34.5 32.3 Other countries 58.1 55.8 Total long-lived assets $ 385.8 $ 393.0 We purchase a substantial portion of our inventory from contract manufacturers and vendors located primarily in Taiwan, Thailand, and Malaysia. During the three and six months ended December 26, 2020, our net inventory purchases from a single contract manufacturer, which represented 10% or greater of total net purchases, were concentrated with two contract manufacturers, who collectively accounted for 67% and 65%

Subsequent Event

Subsequent Event	6 Months Ended
	Dec. 26, 2020
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On January 18, 2021, Lumentum and Coherent, Inc. (“Coherent”) entered into a merger agreement (the “Merger Agreement”), under which Lumentum will acquire all outstanding shares of Coherent common stock. Each share of Coherent common stock will be exchanged for $100 in cash and 1.1851 shares of Lumentum common stock, subject to the terms of the Merger Agreement. As of the date of the Merger Agreement, the total transaction consideration is approximately $5.7 billion. Coherent stockholders will own approximately 27% of the co mbined company at closing. The Merger Agreement contains certain termination rights for both Lumentum and Coherent and provides that upon termination of the Merger Agreement under specified circumstances (including termination by Coherent to accept a superior proposal), Coherent may be required to pay Lumentum a termination fee of $217.6 million. The Merger Agreement further provides that upon termination of the Merger Agreement under specified circumstances (including termination by Lumentum to accept a superior proposal), Lumentum may be required to pay Coherent a termination fee of $337.7 million, and if the Merger Agreement is terminated for failure to obtain antitrust approval from a Chinese governmental entity, Lumentum may be required to pay Coherent a termination fee of $279.0 million. The total transaction consideration will be funded by a combination of approximately $3.2 billion in Lumentum common stock (based on the closing price of Lumentum common stock on the date preceding the Merger Agreement), $2.1 billion in new debt, and the remaining amount from the cash balances of the combined company. Lumentum entered into a commitment letter with Deutsche Bank Securities Inc. and Deutsche Bank AG New York Branch (collectively, “Deutsche Bank”), pursuant to which, subject to the terms and conditions set forth therein, Deutsche Bank has committed to provide a senior secured term loan facility in an aggregate principal amount of up to $2.1 billion. The Boards of Directors of Lumentum and Coherent have unanimously approved the transaction and the Merger Agreement. The transaction is subject to customary closing conditions, including the absence of certain legal impediments, the expiration or termination of the required waiting periods under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, antitrust approvals in other applicable jurisdictions, including China and South Korea, the effectiveness of a registration statement on Form S-4 registering the shares of Lumentum common stock to be issued in connection with the transaction, and approval by the holders of a majority of the outstanding shares of Lumentum common stock and Coherent common stock. The transaction is not subject to any financing condition. The transaction is expected to be completed in the second half of calendar 2021.

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Dec. 26, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The preparation of the condensed consolidated financial statements in accordance with U.S. generally accepted accounting principles (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in our condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and various other assumptions believed to be reasonable. Although these estimates are based on management’s best knowledge of current events and actions that may impact the Company in the future, actual results may be different from the estimates. Our critical accounting policies are those that affect our financial statements materially and involve difficult, subjective or complex judgments by management. Those policies are inventory valuation, revenue recognition, income taxes, and goodwill. The COVID-19 pandemic has created and may continue to create significant uncertainty in global financial markets, which has disrupted and harmed, and may continue to disrupt and harm, the Company's business, financial condition, and results of operations. The extent of the impact of COVID-19 on the Company's operational and financial performance will depend on certain developments, including but not limited to the duration and spread of the outbreak, duration of local, state and federal issued public health orders in each jurisdiction where we operate or in which our customers and suppliers operate, impact on our customers and our sales cycles, impact on our supply chain and manufacturing partners, impact on our employees and impact on regional and worldwide economies and financial markets in general, all of which are uncertain and cannot be predicted.
Fiscal Years	Fiscal Years We utilize a 52-53 week fiscal year ending on the Saturday closest to June 30th. Every fifth or sixth fiscal year will have a 53-week period. The additional week in a 53-week year is added to the third quarter, making such quarter consist of 14 weeks. Our fiscal 2021 is a 53-week year ending on July 3, 2021, with the quarter ended December 26, 2020 being a 13-week quarterly period and our third quarter ending on April 3, 2021 being a 14-week quarterly period. Our fiscal 2020 was a 52-week year that ended on June 27, 2020, with the quarter ended December 28, 2019 being a 13-week quarterly period.
Principles of Consolidation	Principles of ConsolidationThese interim unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All inter-company transactions and balances have been eliminated in consolidation.
Accounting Policies, Accounting Pronouncements Recently Adopted and Accounting Pronouncements Not Yet Effective	Accounting PoliciesThe accompanying condensed consolidated financial statements and accompanying related notes should be read in conjunction with the audited consolidated financial statements and related notes included in our Annual Report on Form 10-K for the fiscal year ended June 27, 2020. Accounting Pronouncements Recently Adopted In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 modifies the disclosure requirements on transfers between Level 1 and Level 2, valuation processes of Level 3 fair value measurements, and the categorization by level for items that are not measured at fair value, but for which the fair value is required to be disclosed. We adopted ASU 2018-13 in the first quarter of fiscal 2021 with no impact to our condensed consolidated financial statements. In August 2018, FASB issued ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. This standard requires capitalization of the implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. Further, the standard also requires the Company to expense the capitalized implementation costs of a hosting arrangement over the term of the hosting arrangement. We adopted ASU 2018-15 in the first quarter of fiscal 2021 with no impact to our condensed consolidated financial statements. In June 2016, FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments and a subsequent amendment, ASU 2018-19 (collectively, Topic 326). Topic 326 requires measurement and recognition of expected credit losses for financial assets held. We adopted ASU 2016-13 using the modified-retrospective approach in the first quarter of fiscal 2021 with no material impact to our condensed consolidated financial statements. With the adoption of Topic 326, we are now assessing whether unrealized losses have resulted from a credit loss or other factors. We believe none of our unrealized losses on available-for-sale investments were other-than temporary or were attributable to credit losses as of December 26, 2020 and June 27, 2020. We review our available-for-sale investments on a quarterly basis to identify a potential other-than-temporary impairment. The investments with unrealized losses consisted primarily of corporate debt securities, and given the extent of the unrealized loss positions, the issuers' high credit ratings and the near-term market conditions, we believe our unrealized losses are temporary. We also do not have an intent to sell our investments and would not be required to sell them before they recover. The adoption of Topic 326 did not significantly change our approach to the valuation of trade receivables. We determine whether there is an expected loss on our accounts receivable by reviewing all available data, including our customers' latest available financial statements, their credit standing and historical collection experience, as well as current and future market and economic conditions. As of December 26, 2020 and June 27, 2020, the allowance for credit losses on our trade receivables was $1.7 million and $1.8 million, respectively. Accounting Pronouncements Not Yet Effective In August 2020, FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , which simplifies the accounting for convertible instruments by removing the separation models for (1) convertible debt with a cash conversion feature and (2) convertible instruments with a beneficial conversion feature. As a result, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost. Also, ASU 2020-06 requires the application of the if-converted method for calculating diluted earnings per share and the treasury stock method will be no longer available. The new guidance is effective for fiscal years beginning after December 15, 2021, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. ASU 2020-06 is effective for us in our first quarter of fiscal year 2023. We are currently evaluating the impact of ASU 2020-06 on our condensed consolidated financial statements. In December 2019, FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (Topic 740), which is intended to simplify various aspects related to accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and which also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for us at the beginning of fiscal year 2022, including interim periods within that reporting period, although early adoption is permitted. We are currently evaluating the impact of ASU 2019-12 on our condensed consolidated financial statements. In August 2018, FASB issued ASU 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans
Fair Value Measurements	We determine fair value based on the fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value assumes that the transaction to sell the asset or transfer the liability occurs in the principal or most advantageous market for the asset or liability and establishes that the fair value of an asset or liability shall be determined based on the assumptions that market participants would use in pricing the asset or liability. The classification of a financial asset or liability within the hierarchy is based upon the lowest level input that is significant to the fair value measurement. The fair value hierarchy prioritizes the inputs into three levels that may be used to measure fair value: Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2: Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3: Inputs are unobservable inputs based on our assumptions. The fair value of our Level 1 financial instruments, such as money market funds and U.S. Treasury securities, which are traded in active markets, is based on quoted market prices for identical instruments. The fair value of our Level 2 fixed income securities is obtained from an independent pricing service, which may use quoted market prices for identical or comparable instruments or model driven valuations using observable market data or inputs corroborated by observable market data. Our marketable securities are held by custodians who obtain investment prices from a third-party pricing provider that incorporates standard inputs in various asset price models. Our procedures include controls to ensure that appropriate fair values are recorded, including comparing the fair values obtained from our pricing service against fair values obtained from another independent source. Assets Measured at Fair Value on a Non-Recurring Basis We periodically review our intangible and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Determination of recoverability is based on the lowest level of identifiable estimated undiscounted cash flows resulting from use of the asset and its eventual disposition. If not recoverable, an impairment loss would be calculated based on the excess of the carrying amount over the fair value.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Dec. 26, 2020
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted net income (loss) attributable to common stockholders per share	The following table sets forth the computation of basic and diluted net income per share ( in millions, except per share data ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Numerator: Net income $ 83.2 $ 49.1 $ 150.3 $ 96.7 Denominator: Basic weighted average common shares outstanding 75.6 76.8 75.5 76.9 Effect of dilutive securities from stock-based benefit plans 0.7 0.7 0.8 0.7 Shares issuable assuming conversion of the 2024 Notes 2.1 0.5 2.0 0.2 Diluted weighted average common shares outstanding 78.4 78.0 78.3 77.8 Net income per share: Basic $ 1.10 $ 0.64 $ 1.99 $ 1.26 Diluted $ 1.06 $ 0.63 $ 1.92 $ 1.24

Cash, Cash Equivalents and Sh_2

Cash, Cash Equivalents and Short-term Investments (Tables)	6 Months Ended
	Dec. 26, 2020
Cash and Cash Equivalents [Abstract]
Schedule of cash, cash equivalents and short-term investments	The following table summarizes our cash, cash equivalents and short-term investments by category for the periods presented ( in millions ): Amortized Gross Gross Fair Value December 26, 2020: Cash $ 107.7 $ — $ — $ 107.7 Cash equivalents: Commercial paper 10.0 — — 10.0 Money market funds 203.6 — — 203.6 Total cash and cash equivalents $ 321.3 $ — $ — $ 321.3 Short-term investments: Certificates of deposit $ 4.9 $ — $ — $ 4.9 Commercial paper 112.8 — — 112.8 Corporate debt securities 523.2 0.5 (0.2) 523.5 U.S. Agency securities 60.6 — — 60.6 U.S. Treasury securities 677.0 0.2 — 677.2 Total short-term investments $ 1,378.5 $ 0.7 $ (0.2) $ 1,379.0 June 27, 2020: Cash $ 114.2 $ — $ — $ 114.2 Cash equivalents: Money market funds 159.6 — — 159.6 U.S. Treasury securities 24.2 — — 24.2 Total cash and cash equivalents $ 298.0 $ — $ — $ 298.0 Short-term investments: Certificates of deposit $ 12.9 $ — $ — $ 12.9 Commercial paper 179.9 0.3 — 180.2 Corporate debt securities 435.0 1.7 (0.1) 436.6 Foreign government bonds 1.7 — — 1.7 U.S. Agency securities 59.5 — — 59.5 U.S. Treasury securities 563.9 1.0 — 564.9 Total short-term investments $ 1,252.9 $ 3.0 $ (0.1) $ 1,255.8
Summary of unrealized losses on cash equivalents and short-term investments	The following table summarizes unrealized losses on our cash equivalents and short-term investments by category and length of time the investment has been in a continuous unrealized loss position as of the periods presented ( in millions ): Less than 12 months Fair Value Unrealized Losses December 26, 2020: U.S. Agency securities $ 36.6 $ — Commercial paper 72.6 — Corporate debt securities 246.1 (0.2) U.S. government bonds 151.8 — Total $ 507.1 $ (0.2) June 27, 2020: Certificates of deposit $ 3.1 $ — Commercial paper 51.1 — Corporate debt securities 96.5 (0.1) Foreign government bonds 1.7 — U.S. Agency securities 47.0 — U.S. government bonds 159.8 — Total $ 359.2 $ (0.1)
Classification of investments in debt securities by contractual maturities	The following table classifies our short-term investments by contractual maturities ( in millions ): December 26, 2020 June 27, 2020 Amortized Cost Fair Value Amortized Cost Fair Value Due in 1 year $ 1,036.5 $ 1,036.9 $ 1,237.4 $ 1,239.9 Due in 1 year through 5 years 342.0 342.1 15.5 15.9 $ 1,378.5 $ 1,379.0 $ 1,252.9 $ 1,255.8

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Dec. 26, 2020
Fair Value Disclosures [Abstract]
Summary of financial assets measured at fair value on a recurring basis	Financial assets measured at fair value on a recurring basis are summarized below ( in millions ): Level 1 Level 2 Level 3 Total December 26, 2020: (1) Assets: Cash equivalents: Commercial paper $ — $ 10.0 $ — $ 10.0 Money market funds 203.6 — — 203.6 Short-term investments: Certificates of deposit — 4.9 — 4.9 Commercial paper — 112.8 — 112.8 Corporate debt securities — 523.5 — 523.5 U.S. Agency securities — 60.6 — 60.6 U.S. Treasury securities 677.2 — — 677.2 Total assets $ 880.8 $ 711.8 $ — $ 1,592.6 (1) Excludes $107.7 million in cash held in our bank accounts at December 26, 2020. Level 1 Level 2 Level 3 Total June 27, 2020: (1) Assets: Cash equivalents: Money market funds $ 159.6 $ — $ — $ 159.6 U.S. Treasury securities 24.2 — — 24.2 Short-term investments: Certificates of deposit — 12.9 — 12.9 Commercial paper — 180.2 — 180.2 Corporate debt securities — 436.6 — 436.6 Foreign government bonds — 1.7 — 1.7 U.S. Agency securities — 59.5 — 59.5 U.S. Treasury securities 564.9 — — 564.9 Total assets $ 748.7 $ 690.9 $ — $ 1,439.6 (1) Excludes $114.2 million in cash held in our bank accounts as of June 27, 2020.
Fair value measurements, recurring and nonrecurring	The carrying amounts and estimated fair values of the 2026 Notes and the 2024 Notes are as follows for the periods presented ( in millions ): December 26, 2020 June 27, 2020 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value 2026 Notes $ 769.1 $ 1,312.5 $ 749.7 $ 1,070.2 2024 Notes 380.3 765.1 370.6 620.0 $ 1,149.4 $ 2,077.6 $ 1,120.3 $ 1,690.2

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	6 Months Ended
	Dec. 26, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of components of inventories	The components of inventories were as follows ( in millions ): December 26, 2020 June 27, 2020 Raw materials and purchased parts $ 70.4 $ 57.9 Work in process 84.2 67.6 Finished goods 52.5 63.4 Inventories $ 207.1 $ 188.9
Schedule of operating lease, right-of-use assets	Operating lease right-of-use assets, net were as follows ( in millions ): December 26, 2020 June 27, 2020 Operating lease right-of-use assets $ 88.7 $ 90.3 Less: accumulated amortization (16.9) (11.6) Operating lease right-of-use assets, net $ 71.8 $ 78.7
Schedule of components of property, plant and equipment, net	The components of property, plant and equipment, net were as follows ( in millions ): December 26, 2020 June 27, 2020 Land $ 44.1 $ 44.1 Buildings and improvement 118.1 114.8 Machinery and equipment 517.2 487.0 Computer equipment and software 28.7 27.5 Furniture and fixtures 8.6 7.2 Leasehold improvements 29.5 27.8 Finance lease right-of-use assets 28.1 28.1 Construction in progress 45.6 54.7 819.9 791.2 Less: Accumulated depreciation (434.1) (398.2) Property, plant and equipment, net $ 385.8 $ 393.0
Schedule of components of other current liabilities	The components of other current liabilities were as follows (in millions) : December 26, 2020 June 27, 2020 Restructuring accrual and related charges (1) $ 4.6 $ 5.2 Warranty accrual (2) 5.7 5.0 Deferred revenue and customer deposits 0.5 1.9 Finance lease liabilities, current 0.3 0.6 Income tax payable (3) 51.5 28.8 Other current liabilities 2.7 2.8 Other current liabilities $ 65.3 $ 44.3 (1) Refer to “Note 11. Restructuring and Related Charges.” (2) Refer to “Note 14. Commitments and Contingencies.” (3) Refer to “Note 12. Income Taxes.”
Schedule of components of other non-current liabilities	The components of other non-current liabilities were as follows ( in millions ): December 26, 2020 June 27, 2020 Asset retirement obligations $ 4.7 $ 4.6 Pension accrual 12.2 11.8 Unrecognized tax benefit 18.9 17.3 Other non-current liabilities 2.3 2.3 Other non-current liabilities $ 38.1 $ 36.0

Leases (Tables)

Leases (Tables)	6 Months Ended
	Dec. 26, 2020
Leases [Abstract]
Schedule of lease costs	The components of lease costs, lease term, and discount rate are as follows: Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Finance lease cost ( in millions ): Amortization of right-of-use assets $ 0.1 $ 4.3 $ 0.3 $ 8.2 Interest — — — 0.1 Operating lease cost 3.6 4.0 7.2 8.0 Short-term and variable lease costs 1.2 1.0 2.3 2.1 Sublease income (0.7) (0.6) (1.4) (1.2) Total lease cost $ 4.2 $ 8.7 $ 8.4 $ 17.2 December 26, 2020 June 27, 2020 Weighted average remaining lease term ( in years ): Operating leases 8.0 8.6 Finance leases 0.5 1.0 Weighted average discount rate: Operating leases 3.5 % 3.5 % Finance leases 4.4 % 4.4 %
Schedule of operating lease liability	As of December 26, 2020, maturities of our operating and finance lease liabilities, which do not include short-term leases and variable lease payments, were as follows ( in millions ): Fiscal Years Operating Leases (1) Finance Leases Total Remainder of 2021 $ 6.8 $ 0.3 $ 7.1 2022 13.1 — 13.1 2023 11.8 — 11.8 2024 10.1 — 10.1 2025 6.7 — 6.7 Thereafter 26.3 — 26.3 Total minimum lease payments $ 74.8 $ 0.3 $ 75.1 Less: amount representing interest (8.9) — (8.9) Present value of total lease liabilities $ 65.9 $ 0.3 $ 66.2 (1) Non-cancellable sublease proceeds for the remainder of fi scal 2021, and fiscal 2022, and 2023 of $1.5 million, $2.3 million, and $0.6 million, respectively, are not included in the table above.
Schedule of finance lease liability	As of December 26, 2020, maturities of our operating and finance lease liabilities, which do not include short-term leases and variable lease payments, were as follows ( in millions ): Fiscal Years Operating Leases (1) Finance Leases Total Remainder of 2021 $ 6.8 $ 0.3 $ 7.1 2022 13.1 — 13.1 2023 11.8 — 11.8 2024 10.1 — 10.1 2025 6.7 — 6.7 Thereafter 26.3 — 26.3 Total minimum lease payments $ 74.8 $ 0.3 $ 75.1 Less: amount representing interest (8.9) — (8.9) Present value of total lease liabilities $ 65.9 $ 0.3 $ 66.2 (1) Non-cancellable sublease proceeds for the remainder of fi scal 2021, and fiscal 2022, and 2023 of $1.5 million, $2.3 million, and $0.6 million, respectively, are not included in the table above.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	6 Months Ended
	Dec. 26, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of changes in goodwill	The following table presents our goodwill balance by the reportable segments as of December 26, 2020 and June 27, 2020 ( in millions) : Optical Communications Commercial Lasers Total Balance as of December 26, 2020 and June 27, 2020 $ 363.5 $ 5.4 $ 368.9
Acquired developed technology and other intangibles	The following tables present details of our other intangibles as of the periods presented ( in millions, except for weighted average remaining amortization period ): December 26, 2020 Gross Carrying Amounts Accumulated Amortization Net Carrying Amounts Weighted average remaining amortization period (years) Acquired developed technologies $ 381.5 $ (207.2) $ 174.3 3.4 Customer relationships 149.3 (48.4) 100.9 6.0 In-process research and development 10.0 — 10.0 n/a Order backlog 22.0 (22.0) — — Other intangibles 2.7 (2.7) — — Total intangible assets $ 565.5 $ (280.3) $ 285.2 June 27, 2020 Gross Carrying Amounts Accumulated Amortization Net Carrying Amounts Weighted average remaining amortization period (years) Acquired developed technologies $ 371.5 $ (176.9) $ 194.6 3.7 Customer relationships 149.3 (37.1) 112.2 6.5 In-process research and development 10.0 — 10.0 n/a Order backlog 22.0 (22.0) — — Other intangibles 2.7 (2.7) — — Total intangible assets $ 555.5 $ (238.7) $ 316.8
Details of amortization expense	The following table presents details of amortization for the periods presented (in millions ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Cost of sales $ 15.0 $ 12.4 $ 30.0 $ 24.9 Selling, general and administrative 5.9 6.2 11.6 12.5 Total amortization of intangibles $ 20.9 $ 18.6 $ 41.6 $ 37.4
Estimated future amortization expense	Based on the carrying amount of our acquired developed technologies and other intangibles, excluding IPR&D, as of December 26, 2020, and assuming no future impairment of the underlying assets, the estimated future amortization is as follows (in millions) : Fiscal Years Remainder of 2021 $ 42.3 2022 82.1 2023 58.6 2024 38.8 2025 27.7 Thereafter 25.7 Total future amortization $ 275.2

Debt (Tables)

Debt (Tables)	6 Months Ended
	Dec. 26, 2020
Debt Disclosure [Abstract]
Schedule of convertible notes	Our convertible notes consisted of the following components as of the periods presented ( in millions ): Liability component: December 26, 2020 June 27, 2020 2024 Notes (1) 2026 Notes 2024 Notes (1) 2026 Notes Principal $ 450.0 $ 1,050.0 $ 450.0 $ 1,050.0 Unamortized debt discount and debt issuance costs (69.7) (280.9) (79.4) (300.3) Net carrying amount of the liability component $ 380.3 $ 769.1 $ 370.6 $ 749.7 (1) Since the closing price of our stock exceeded $78.80 (or 130% of the conversion price of $60.62 ) for 20 of the last 30 trading days of the second quarter of fiscal 2021, the 2024 Notes have become convertible at the option of the holders. Therefore, the debt component of our 2024 Notes as of December 26, 2020 was reclassified to current liabilities in our condensed consolidated balance sheet.
Schedule of interest expense	The following table sets forth interest expense information related to the convertible notes for the periods presented (in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Contractual interest expense $ 1.6 $ 0.5 $ 3.2 $ 0.7 Amortization of the debt discount and debt issuance costs 14.7 6.2 29.1 10.8 Total interest expense $ 16.3 $ 6.7 $ 32.3 $ 11.5
Schedule of future interest and principal payments related to our convertible notes	The future interest and principal payments related to our convertible notes are as follows as of December 26, 2020 (in millions) : Fiscal Years 2024 Notes 2026 Notes Total Remainder of 2021 $ 0.6 $ 2.6 $ 3.2 2022 1.1 5.3 6.4 2023 1.1 5.3 6.4 2024 451.1 5.3 456.4 2025 — 5.3 5.3 Thereafter — 1,057.7 1,057.7 Total convertible notes payments $ 453.9 $ 1,081.5 $ 1,535.4

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Dec. 26, 2020
Equity [Abstract]
Schedule of accumulated other comprehensive income (loss)	The changes in accumulated other comprehensive income (loss) were as follows for the periods as presented ( in millions ): Foreign currency translation adjustments, net of tax (1) Defined benefit obligations, net of tax (2) Unrealized gain (loss) on available-for-sale securities, net of tax Total Beginning balance as of June 27, 2020 $ 9.7 $ (4.2) $ 2.4 $ 7.9 Other comprehensive loss — — (1.5) (1.5) Ending balance as of September 26, 2020 9.7 (4.2) 0.9 6.4 Other comprehensive loss (3) — — (0.4) (0.4) Ending balance as of December 26, 2020 $ 9.7 $ (4.2) $ 0.5 $ 6.0 Beginning balance as of June 29, 2019 $ 9.7 $ (3.5) $ 0.9 $ 7.1 Other comprehensive income — — 0.1 0.1 Ending balance as of September 28, 2019 9.7 (3.5) 1.0 7.2 Other comprehensive loss — — (0.2) (0.2) Ending balance as of December 28, 2019 $ 9.7 $ (3.5) $ 0.8 $ 7.0 (1) In fiscal 2019, as a result of significant changes in economic facts and circumstances, primarily due to the acquisition of Oclaro, we established the functional currency for our worldwide operations as the U.S. dollar. Translation adjustments reported prior to December 10, 2018, remain as a component of accumulated other comprehensive income in our condensed consolidated balance sheets, until all or a part of the investment in the subsidiaries is sold or liquidated. (2) We evaluate the assumptions over the fair value of our defined benefit obligations annually and make changes as necessary.

Restructuring and Related Cha_2

Restructuring and Related Charges (Tables)	6 Months Ended
	Dec. 26, 2020
Restructuring and Related Activities [Abstract]
Summary of activity of restructuring and related charges	The following table summarizes the activity of restructuring and related charges during the three and six months ended December 26, 2020 and December 28, 2019 ( in millions ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Balance as of beginning of period $ 4.4 $ 10.7 $ 5.2 $ 14.6 Charges 0.2 0.9 0.2 2.2 Payments — (6.6) (0.8) (11.8) Balance as of end of period $ 4.6 $ 5.0 $ 4.6 $ 5.0

Equity (Tables)

Equity (Tables)	6 Months Ended
	Dec. 26, 2020
Equity [Abstract]
Schedule of impact on results of operations of recording stock-based compensation by function	The impact on our results of operations of recording stock-based compensation by function for the three and six months ended December 26, 2020 and December 28, 2019 was as follows (in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Cost of sales $ 4.8 $ 4.1 $ 8.5 $ 8.3 Research and development 5.1 4.1 9.5 7.9 Selling, general and administrative 14.2 12.0 25.6 20.7 Total stock-based compensation $ 24.1 $ 20.2 $ 43.6 $ 36.9
Schedule of income tax benefit associated with stock-based compensation	Total income tax benefit associated with stock-based compensation recognized in our consolidated statements of operations during the years presented was as follows (in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Income tax benefit associated with stock-based compensation $ 3.6 $ 3.8 $ 8.8 $ 6.6
Summary of awards activity	The following table summarizes our awards activity for the six months ended December 26, 2020 (in millions, except per share amounts) : Restricted Stock Units Performance Stock Units Number of Shares Weighted-Average Grant Date Fair Value per Share Number of Shares Weighted-Average Grant Date Fair Value per Share Balance as of June 27, 2020 1.9 $ 56.6 0.3 $ 60.6 Granted 1.1 86.7 0.2 86.7 Vested (0.8) 56.1 (0.1) 57.7 Canceled (0.1) 62.3 — 71.8 Balance as of December 26, 2020 2.1 $ 72.2 0.4 $ 73.3
Summary of awards available for grant	A summary of awards available for grant is as follows (in millions) : Awards Available for Grant Balance as of June 27, 2020 3.5 Granted (1.3) Canceled 0.1 Balance as of December 26, 2020 2.3

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Dec. 26, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of changes in warranty reserve	The following table presents the changes in our warranty reserve during the three and six months ended December 26, 2020 and December 28, 2019 ( in millions ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Balance as of beginning of period $ 7.6 $ 7.0 $ 5.0 $ 7.5 Provision for warranty 0.2 0.6 4.1 1.8 Utilization of reserve (2.1) (0.8) (3.4) (2.5) Balance as of end of period $ 5.7 $ 6.8 $ 5.7 $ 6.8

Operating Segments and Geogra_2

Operating Segments and Geographic Information (Tables)	6 Months Ended
	Dec. 26, 2020
Segment Reporting [Abstract]
Schedule of information on reportable segments	Information on reportable segments utilized by our CODM is as follows ( in millions) : Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Net revenue: OpComms $ 449.1 $ 409.4 $ 877.6 $ 825.5 Lasers 29.7 48.4 53.6 82.2 Net revenue $ 478.8 $ 457.8 $ 931.2 $ 907.7 Gross profit: OpComms $ 241.8 $ 196.4 $ 466.6 $ 388.3 Lasers 14.1 20.4 24.5 34.6 Total segment gross profit 255.9 216.8 491.1 422.9 Unallocated corporate items: Stock-based compensation (4.8) (4.1) (8.5) (8.3) Amortization of acquired intangibles (15.0) (12.4) (30.0) (24.9) Amortization of inventory fair value adjustments — (2.1) — (4.3) Inventory and fixed asset write down due to product line exits (0.1) (2.6) (0.4) (3.7) Integration related costs — — — (3.4) Other charges (1) (6.4) (6.5) (16.9) (21.5) Gross profit $ 229.6 $ 189.1 $ 435.3 $ 356.8 (1) “Other charges” of unallocated corporate items for the three and six months ended December 26, 2020 include costs of transferring product lines to new production facilities, including Thailand of $0.4 million and $2.5 million, respectively. We also incurred excess and obsolete inventory charges driven by U.S. trade restrictions and the related decline in demand from Hua wei of $0.8 million and $6.7 million during the three and six months ended December 26, 2020, respectively. In addition, during the three months ended December 26, 2020, we incurred $4.6 million of impairment charges associ ated with excess capacity related to our Fiber laser business. “Other charges” of unallocated corporate items for the three and six months ended December 28, 2019 include costs of transferring product lines to new production facilities, including Thailand of $2.0 million and $8.1 million, respectively. We also incurred excess and obsolete inventory charges driven by the decline in demand from Huawei of $6.0 million and $12.7 million during the three and six months ended December 28, 2019.
Schedule of concentration risks	The table below discloses our total net revenue attributable to each of our two reportable segments. In addition, the table sets forth the percentage of our total net revenue attributable to our product offerings which serve Telecom and Datacom, and Consumer and Industrial markets which accounted for 10% or more of our total net revenue during the periods presented ( in millions, except percentage data ): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 OpComms: Telecom and Datacom $ 286.2 59.8 % $ 266.3 58.2 % $ 547.5 58.8 % $ 514.4 56.6 % Consumer and Industrial 162.9 34.0 143.1 31.2 330.1 35.4 311.1 34.3 Total OpComms $ 449.1 93.8 % $ 409.4 89.4 % $ 877.6 94.2 % $ 825.5 90.9 % Lasers 29.7 6.2 48.4 10.6 53.6 5.8 82.2 9.1 Total Revenue $ 478.8 $ 457.8 $ 931.2 $ 907.7
Schedule of revenue by geographic region	The following table presents net revenue by the three geographic regions we operate in and net revenue from countries that represented 10% or more of our total net revenue (in millions, except percentage data): Three Months Ended Six Months Ended December 26, 2020 December 28, 2019 December 26, 2020 December 28, 2019 Net revenue: Amount % of Total Amount % of Total Amount % of Total Amount % of Total Americas: United States $ 39.7 8.3 % $ 43.4 9.5 % $ 60.0 6.4 % $ 80.3 8.8 % Mexico 51.3 10.7 26.2 5.7 91.1 9.8 55.1 6.1 Other Americas 4.0 0.8 0.7 0.2 6.8 0.8 1.8 0.2 Total Americas $ 95.0 19.8 % $ 70.3 15.4 % $ 157.9 17.0 % $ 137.2 15.1 % Asia-Pacific: Hong Kong $ 148.0 30.9 % $ 144.5 31.6 % $ 292.4 31.4 % $ 278.3 30.7 % Philippines 40.6 8.5 4.8 1.0 103.4 11.1 29.8 3.3 South Korea 66.0 13.8 85.0 18.6 122.0 13.1 176.6 19.5 Other Asia-Pacific 94.0 19.6 116.1 25.4 185.6 19.9 216.4 23.8 Total Asia-Pacific $ 348.6 72.8 % $ 350.4 76.6 % $ 703.4 75.5 % $ 701.1 77.3 % EMEA $ 35.2 7.4 % $ 37.1 8.0 % $ 69.9 7.5 % $ 69.4 7.6 % Total net revenue $ 478.8 $ 457.8 $ 931.2 $ 907.7
Schedule of estimated revenue expected to be recognized in the future related to performance obligations	The following table includes estimated revenue expected to be recognized in the future for backlog related performance obligations that are unsatisfied as of December 26, 2020 ( in millions ): Less than 1 year 1-2 years Greater than 2 years Total Performance obligations $475.4 $2.4 $— $477.8
Schedule of changes in contract balances	The following table reflects the changes in contract balances as of December 26, 2020 ( in millions, except percentages ): Contract balances Balance sheet location December 26, 2020 June 27, 2020 Change Percentage Change Accounts receivable, net Accounts receivable, net $276.7 $233.5 $43.2 18.5% Deferred revenue and customer deposits Other current liabilities $0.5 $1.9 $(1.4) (73.7)%
Schedule of long-lived assets by geographic region	Long-lived assets, namely net property, plant and equipment, net, were identified based on the physical location of the assets in the corresponding geographic areas as of the periods indicated (in millions) : December 26, 2020 June 27, 2020 Property, plant and equipment, net United States $ 138.6 $ 139.1 Thailand 112.1 122.6 China 42.5 43.2 Japan 34.5 32.3 Other countries 58.1 55.8 Total long-lived assets $ 385.8 $ 393.0

Recently Issued Accounting Pr_2

Recently Issued Accounting Pronouncements - Narrative (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Accounting Changes and Error Corrections [Abstract]
Accounts receivable allowance for credit losses	$ 1.7	$ 1.8

Earnings Per Share - Computatio

Earnings Per Share - Computation of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Dec. 26, 2020	Sep. 26, 2020	Dec. 28, 2019	Sep. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Numerator:
Net income	$ 83.2	$ 67.1	$ 49.1	$ 47.6	$ 150.3	$ 96.7
Denominator:
Basic weighted average common shares outstanding (in shares)	75.6		76.8		75.5	76.9
Effect of dilutive securities from stock-based benefits plan (in shares)	0.7		0.7		0.8	0.7
Shares issuable assuming conversion of the 2024 Notes (in shares)	2.1		0.5		2	0.2
Diluted weighted average common shares outstanding (in shares)	78.4		78		78.3	77.8
Basic (in usd per share)	$ 1.10		$ 0.64		$ 1.99	$ 1.26
Diluted (in usd per share)	$ 1.06		$ 0.63		$ 1.92	$ 1.24

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - $ / shares	3 Months Ended	6 Months Ended
	Dec. 26, 2020	Dec. 26, 2020	Dec. 31, 2019	Mar. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares (in shares)	0	500,000
Convertible Debt | 2026 Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share
Conversion price (in usd per share)	$ 99.29	$ 99.29	$ 99.29
Convertible Debt | 2024 Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share
Conversion price (in usd per share)	$ 60.62	$ 60.62		$ 60.62

Cash, Cash Equivalents and Sh_3

Cash, Cash Equivalents and Short-term Investments - Summary of Cash, Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Cash and cash equivalents:
Cash	$ 107.7	$ 114.2
Cash and cash equivalents	321.3	298
Short-term investments:
Amortized Cost	1,378.5	1,252.9
Gross Unrealized Gains	0.7	3
Gross Unrealized Losses	(0.2)	(0.1)
Fair Value	1,379	1,255.8
Certificates of deposit
Short-term investments:
Amortized Cost	4.9	12.9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	4.9	12.9
Commercial paper
Short-term investments:
Amortized Cost	112.8	179.9
Gross Unrealized Gains	0	0.3
Gross Unrealized Losses	0	0
Fair Value	112.8	180.2
Corporate debt securities
Short-term investments:
Amortized Cost	523.2	435
Gross Unrealized Gains	0.5	1.7
Gross Unrealized Losses	(0.2)	(0.1)
Fair Value	523.5	436.6
Foreign government bonds
Short-term investments:
Amortized Cost		1.7
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		1.7
U.S. Agency securities
Short-term investments:
Amortized Cost	60.6	59.5
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	60.6	59.5
U.S. Treasury securities
Short-term investments:
Amortized Cost	677	563.9
Gross Unrealized Gains	0.2	1
Gross Unrealized Losses	0	0
Fair Value	677.2	564.9
Commercial paper
Cash and cash equivalents:
Cash equivalents	10
Money market funds
Cash and cash equivalents:
Cash equivalents	$ 203.6	159.6
U.S. Treasury securities
Cash and cash equivalents:
Cash equivalents		$ 24.2

Cash, Cash Equivalents and Sh_4

Cash, Cash Equivalents and Short-term Investments - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019	Jun. 27, 2020
Cash and Cash Equivalents [Abstract]
Other income (expense), net	$ (900,000)	$ 1,200,000	$ (300,000)	$ 6,200,000
Income on short-term investments and cash equivalents	1,500,000	$ 3,400,000	3,900,000	$ 7,400,000
Interest receivable in prepayments and other current assets	5,200,000		5,200,000		$ 4,300,000
Unrealized losses, greater than 12 months	$ 0		$ 0		$ 0

Cash, Cash Equivalents and Sh_5

Cash, Cash Equivalents and Short-term Investments - Summary of Unrealized Losses (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Cash and Cash Equivalents
Fair Value, Less than 12 months	$ 507.1	$ 359.2
Unrealized Losses
Unrealized Losses, Less than 12 months	(0.2)	(0.1)
U.S. Agency securities
Cash and Cash Equivalents
Fair Value, Less than 12 months	36.6	47
Unrealized Losses
Unrealized Losses, Less than 12 months	0	0
Certificates of deposit
Cash and Cash Equivalents
Fair Value, Less than 12 months		3.1
Unrealized Losses
Unrealized Losses, Less than 12 months		0
Commercial paper
Cash and Cash Equivalents
Fair Value, Less than 12 months	72.6	51.1
Unrealized Losses
Unrealized Losses, Less than 12 months	0	0
Corporate debt securities
Cash and Cash Equivalents
Fair Value, Less than 12 months	246.1	96.5
Unrealized Losses
Unrealized Losses, Less than 12 months	(0.2)	(0.1)
Foreign government bonds
Cash and Cash Equivalents
Fair Value, Less than 12 months		1.7
Unrealized Losses
Unrealized Losses, Less than 12 months		0
U.S. government bonds
Cash and Cash Equivalents
Fair Value, Less than 12 months	151.8	159.8
Unrealized Losses
Unrealized Losses, Less than 12 months	$ 0	$ 0

Cash, Cash Equivalents and Sh_6

Cash, Cash Equivalents and Short-term Investments - Investments in Debt Securities by Contractual Maturities (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Amortized Cost
Due in 1 year	$ 1,036.5	$ 1,237.4
Due in 1 year through 5 years	342	15.5
Total	1,378.5	1,252.9
Fair Value
Due in 1 year	1,036.9	1,239.9
Due in 1 year through 5 years	342.1	15.9
Total	$ 1,379	$ 1,255.8

Fair Value Measurements - Measu

Fair Value Measurements - Measured on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Assets:
Short-term investments	$ 1,379	$ 1,255.8
Cash held in bank	107.7	114.2
Certificates of deposit
Assets:
Short-term investments	4.9	12.9
Commercial paper
Assets:
Short-term investments	112.8	180.2
Corporate debt securities
Assets:
Short-term investments	523.5	436.6
Foreign government bonds
Assets:
Short-term investments		1.7
U.S. Agency securities
Assets:
Short-term investments	60.6	59.5
U.S. Treasury securities
Assets:
Short-term investments	677.2	564.9
Recurring basis
Assets:
Total assets	1,592.6	1,439.6
Recurring basis | Certificates of deposit
Assets:
Short-term investments	4.9	12.9
Recurring basis | Commercial paper
Assets:
Short-term investments	112.8	180.2
Recurring basis | Corporate debt securities
Assets:
Short-term investments	523.5	436.6
Recurring basis | Foreign government bonds
Assets:
Short-term investments		1.7
Recurring basis | U.S. Agency securities
Assets:
Short-term investments	60.6	59.5
Recurring basis | U.S. Treasury securities
Assets:
Short-term investments	677.2	564.9
Recurring basis | Commercial paper
Assets:
Cash equivalents	10
Recurring basis | Money market funds
Assets:
Cash equivalents	203.6	159.6
Recurring basis | U.S. Treasury securities
Assets:
Cash equivalents		24.2
Recurring basis | Level 1
Assets:
Total assets	880.8	748.7
Recurring basis | Level 1 | Certificates of deposit
Assets:
Short-term investments	0	0
Recurring basis | Level 1 | Commercial paper
Assets:
Short-term investments	0	0
Recurring basis | Level 1 | Corporate debt securities
Assets:
Short-term investments	0	0
Recurring basis | Level 1 | Foreign government bonds
Assets:
Short-term investments		0
Recurring basis | Level 1 | U.S. Agency securities
Assets:
Short-term investments	0	0
Recurring basis | Level 1 | U.S. Treasury securities
Assets:
Short-term investments	677.2	564.9
Recurring basis | Level 1 | Commercial paper
Assets:
Cash equivalents	0
Recurring basis | Level 1 | Money market funds
Assets:
Cash equivalents	203.6	159.6
Recurring basis | Level 1 | U.S. Treasury securities
Assets:
Cash equivalents		24.2
Recurring basis | Level 2
Assets:
Total assets	711.8	690.9
Recurring basis | Level 2 | Certificates of deposit
Assets:
Short-term investments	4.9	12.9
Recurring basis | Level 2 | Commercial paper
Assets:
Short-term investments	112.8	180.2
Recurring basis | Level 2 | Corporate debt securities
Assets:
Short-term investments	523.5	436.6
Recurring basis | Level 2 | Foreign government bonds
Assets:
Short-term investments		1.7
Recurring basis | Level 2 | U.S. Agency securities
Assets:
Short-term investments	60.6	59.5
Recurring basis | Level 2 | U.S. Treasury securities
Assets:
Short-term investments	0	0
Recurring basis | Level 2 | Commercial paper
Assets:
Cash equivalents	10
Recurring basis | Level 2 | Money market funds
Assets:
Cash equivalents	0	0
Recurring basis | Level 2 | U.S. Treasury securities
Assets:
Cash equivalents		0
Recurring basis | Level 3
Assets:
Total assets	0	0
Recurring basis | Level 3 | Certificates of deposit
Assets:
Short-term investments	0	0
Recurring basis | Level 3 | Commercial paper
Assets:
Short-term investments	0	0
Recurring basis | Level 3 | Corporate debt securities
Assets:
Short-term investments	0	0
Recurring basis | Level 3 | Foreign government bonds
Assets:
Short-term investments		0
Recurring basis | Level 3 | U.S. Agency securities
Assets:
Short-term investments	0	0
Recurring basis | Level 3 | U.S. Treasury securities
Assets:
Short-term investments	0	0
Recurring basis | Level 3 | Commercial paper
Assets:
Cash equivalents	0
Recurring basis | Level 3 | Money market funds
Assets:
Cash equivalents	$ 0	0
Recurring basis | Level 3 | U.S. Treasury securities
Assets:
Cash equivalents		$ 0

Fair Value Measurements - Not R

Fair Value Measurements - Not Recorded at Fair Value on a Recurring Basis Convertible Debt (Details) - Convertible Debt - Level 2 - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Carrying Amount
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings
Convertible senior notes fair value	$ 1,149.4	$ 1,120.3
Estimated Fair Value
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings
Convertible senior notes fair value	2,077.6	1,690.2
2026 Notes | Carrying Amount
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings
Convertible senior notes fair value	769.1	749.7
2026 Notes | Estimated Fair Value
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings
Convertible senior notes fair value	1,312.5	1,070.2
2024 Notes | Carrying Amount
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings
Convertible senior notes fair value	380.3	370.6
2024 Notes | Estimated Fair Value
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings
Convertible senior notes fair value	$ 765.1	$ 620

Balance Sheet Details - Account

Balance Sheet Details - Accounts Receivable Allowances (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts receivable allowance for credit losses	$ 1.7	$ 1.8

Balance Sheet Details - Invento

Balance Sheet Details - Inventories (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials and purchased parts	$ 70.4	$ 57.9
Work in process	84.2	67.6
Finished goods	52.5	63.4
Inventories	$ 207.1	$ 188.9

Balance Sheet Details - Operati

Balance Sheet Details - Operating Lease Right-of-Use Assets (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operating lease right-of-use assets	$ 88.7	$ 90.3
Less: accumulated amortization	(16.9)	(11.6)
Operating lease right-of-use assets, net	$ 71.8	$ 78.7

Balance Sheet Details - Propert

Balance Sheet Details - Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019	Jun. 27, 2020
Property, Plant and Equipment
Property, plant and equipment, gross	$ 819.9		$ 819.9		$ 791.2
Less: Accumulated depreciation	(434.1)		(434.1)		(398.2)
Property, plant and equipment, net	385.8		385.8		393
Depreciation expense	23.8	$ 28.7	47.6	$ 60.3
Land
Property, Plant and Equipment
Property, plant and equipment, gross	44.1		44.1		44.1
Buildings and improvement
Property, Plant and Equipment
Property, plant and equipment, gross	118.1		118.1		114.8
Machinery and equipment
Property, Plant and Equipment
Property, plant and equipment, gross	517.2		517.2		487
Computer equipment and software
Property, Plant and Equipment
Property, plant and equipment, gross	28.7		28.7		27.5
Furniture and fixtures
Property, Plant and Equipment
Property, plant and equipment, gross	8.6		8.6		7.2
Leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, gross	29.5		29.5		27.8
Finance lease right-of-use assets
Property, Plant and Equipment
Finance lease right-of-use assets	28.1		28.1		28.1
Construction in progress
Property, Plant and Equipment
Property, plant and equipment, gross	$ 45.6		$ 45.6		$ 54.7

Balance Sheet Details - Other C

Balance Sheet Details - Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 26, 2020	Sep. 26, 2020	Jun. 27, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Restructuring accrual and related charges	$ 4.6	$ 4.4	$ 5.2	$ 5	$ 10.7	$ 14.6
Warranty accrual	5.7		5
Deferred revenue and customer deposits	0.5		1.9
Finance lease liabilities, current	0.3		0.6
Income tax payable	51.5		28.8
Other current liabilities	2.7		2.8
Other current liabilities	$ 65.3		$ 44.3

Balance Sheet Details - Other N

Balance Sheet Details - Other Non-Current Liabilities (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Asset retirement obligations	$ 4.7	$ 4.6
Pension accrual	12.2	11.8
Unrecognized tax benefit	18.9	17.3
Other non-current liabilities	2.3	2.3
Other non-current liabilities	$ 38.1	$ 36

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	6 Months Ended
	Dec. 26, 2020USD ($)renewal
Lessor, Lease, Description
Sublease income, term	2 years
United Kingdom, Canada, and Japan
Lessor, Lease, Description
Forecasted sublease income | $	$ 4.4
Minimum
Lessor, Lease, Description
Number of renewal options (renewal) | renewal	1
Finance lease term	2 years
Maximum
Lessor, Lease, Description
Finance lease term	4 years

Leases - Lease Costs, Term, and

Leases - Lease Costs, Term, and Discount Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019	Jun. 27, 2020
Leases [Abstract]
Finance lease cost, amortization of right-of-use assets	$ 0.1	$ 4.3	$ 0.3	$ 8.2
Finance lease cost, interest	0	0	0	0.1
Operating lease cost	3.6	4	7.2	8
Short-term and variable lease costs	1.2	1	2.3	2.1
Sublease income	(0.7)	(0.6)	(1.4)	(1.2)
Total lease cost	$ 4.2	$ 8.7	$ 8.4	$ 17.2
Weighted average remaining lease term, operating leases	8 years		8 years		8 years 7 months 6 days
Weighted average remaining lease term, finance leases	6 months		6 months		1 year
Weighted average discount rate, operating leases	3.50%		3.50%		3.50%
Weighted average discount rate, finance leases	4.40%		4.40%		4.40%

Leases - Lease Maturities (Deta

Leases - Lease Maturities (Details) $ in Millions	Dec. 26, 2020USD ($)
Operating Leases
Remainder of 2021	$ 6.8
2022	13.1
2023	11.8
2024	10.1
2025	6.7
Thereafter	26.3
Total minimum lease payments	74.8
Less: amount representing interest	(8.9)
Present value of total lease liabilities	65.9
Finance Leases
Remainder of 2021	0.3
2022	0
2023	0
2024	0
2025	0
Thereafter	0
Total minimum lease payments	0.3
Less: amount representing interest	0
Present value of total lease liabilities	0.3
Total
Remainder of 2021	7.1
2022	13.1
2023	11.8
2024	10.1
2025	6.7
Thereafter	26.3
Total minimum lease payments	75.1
Less: amount representing interest	(8.9)
Present value of total lease liabilities	66.2
Sublease Proceeds
Remainder of 2021	1.5
2022	2.3
2023	$ 0.6

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Schedule of Changes in Goodwill (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Changes in goodwill
Goodwill	$ 368.9	$ 368.9
Optical Communications
Changes in goodwill
Goodwill	363.5	363.5
Commercial Lasers
Changes in goodwill
Goodwill	$ 5.4	$ 5.4

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Narrative (Details) - USD ($)	Oct. 29, 2020	Jun. 27, 2020	Dec. 26, 2020
Business Acquisition
Goodwill impairment		$ 0
In-process research and development | Minimum
Business Acquisition
Useful life			4 years
In-process research and development | Maximum
Business Acquisition
Useful life			9 years
Intellectual property
Business Acquisition
Useful life	5 years
Payments to acquire finite lived intangible assets	$ 10,000,000

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Acquired Developed Technology and Other Intangibles (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Dec. 26, 2020	Jun. 27, 2020
Finite-Lived Intangible Assets
Gross Carrying Amounts	$ 565.5	$ 555.5
Accumulated Amortization	(280.3)	(238.7)
Net Carrying Amounts	285.2	316.8
Acquired developed technologies
Finite-Lived Intangible Assets
Gross Carrying Amounts	381.5	371.5
Accumulated Amortization	(207.2)	(176.9)
Net Carrying Amounts	$ 174.3	$ 194.6
Weighted average remaining amortization period (years)	3 years 4 months 24 days	3 years 8 months 12 days
Customer relationships
Finite-Lived Intangible Assets
Gross Carrying Amounts	$ 149.3	$ 149.3
Accumulated Amortization	(48.4)	(37.1)
Net Carrying Amounts	$ 100.9	$ 112.2
Weighted average remaining amortization period (years)	6 years	6 years 6 months
In-process research and development
Finite-Lived Intangible Assets
Gross Carrying Amounts	$ 10	$ 10
Accumulated Amortization	0	0
Net Carrying Amounts	10	10
Order backlog
Finite-Lived Intangible Assets
Gross Carrying Amounts	22	22
Accumulated Amortization	(22)	(22)
Net Carrying Amounts	0	0
Other intangibles
Finite-Lived Intangible Assets
Gross Carrying Amounts	2.7	2.7
Accumulated Amortization	(2.7)	(2.7)
Net Carrying Amounts	$ 0	$ 0

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Details of Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Finite-Lived Intangible Assets
Amortization of intangibles	$ 20.9	$ 18.6	$ 41.6	$ 37.4
Cost of sales
Finite-Lived Intangible Assets
Amortization of intangibles	15	12.4	30	24.9
Selling, general and administrative
Finite-Lived Intangible Assets
Amortization of intangibles	$ 5.9	$ 6.2	$ 11.6	$ 12.5

Goodwill and Other Intangible_7

Goodwill and Other Intangible Assets - Estimated Future Amortization Expense (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Fiscal Years
Net Carrying Amounts	$ 285.2	$ 316.8
Intangibles excluding in-process research and development
Fiscal Years
Remainder of 2021	42.3
2022	82.1
2023	58.6
2024	38.8
2025	27.7
Thereafter	25.7
Net Carrying Amounts	$ 275.2

Debt - Convertible Notes Narrat

Debt - Convertible Notes Narrative (Details)	1 Months Ended		6 Months Ended
	Dec. 31, 2019USD ($)$ / shares	Mar. 31, 2017USD ($)$ / shares	Dec. 26, 2020USD ($)$ / shares	Dec. 28, 2019USD ($)	Jun. 27, 2020USD ($)
Debt Instrument
Repurchase of common stock			$ 0	$ 200,000,000
Convertible Debt | 2026 Notes
Debt Instrument
Debt, aggregate principal amount	$ 1,050,000,000		$ 1,050,000,000		$ 1,050,000,000
Repayments of debt	196,000,000
Repurchase of common stock	$ 200,000,000
Debt, stated interest rate	0.50%		0.50%	0.50%
Conversion rate	0.0100711
Conversion price (in usd per share) | $ / shares	$ 99.29		$ 99.29
Sale price of common stock (in usd per share) | $ / shares			$ 129.08
Conversion threshold percentage of stock price trigger			130.00%
Number of days to trigger conversion			20 days
Convertible Debt | 2024 Notes
Debt Instrument
Debt, aggregate principal amount		$ 450,000,000	$ 450,000,000		$ 450,000,000
Debt, stated interest rate		0.25%
Conversion rate		0.0164965
Conversion price (in usd per share) | $ / shares		$ 60.62	$ 60.62
Conversion price premium percentage		132.50%
Sale price of common stock (in usd per share) | $ / shares			$ 78.80
Conversion threshold percentage of stock price trigger			130.00%
Number of days to trigger conversion			20 days

Debt - Components of Convertibl

Debt - Components of Convertible Notes (Details) - Convertible Debt - USD ($)	6 Months Ended
	Dec. 26, 2020	Jun. 27, 2020	Dec. 31, 2019	Mar. 31, 2017
2024 Notes
Liability component:
Principal	$ 450,000,000	$ 450,000,000		$ 450,000,000
Unamortized debt discount and debt issuance costs	(69,700,000)	(79,400,000)
Net carrying amount of the liability component	$ 380,300,000	370,600,000
Sale price of common stock (in usd per share)	$ 78.80
Conversion threshold percentage of stock price trigger	130.00%
Conversion price (in usd per share)	$ 60.62			$ 60.62
Number of days to trigger conversion	20 days
2026 Notes
Liability component:
Principal	$ 1,050,000,000	1,050,000,000	$ 1,050,000,000
Unamortized debt discount and debt issuance costs	(280,900,000)	(300,300,000)
Net carrying amount of the liability component	$ 769,100,000	$ 749,700,000
Sale price of common stock (in usd per share)	$ 129.08
Conversion threshold percentage of stock price trigger	130.00%
Conversion price (in usd per share)	$ 99.29		$ 99.29
Number of days to trigger conversion	20 days

Debt - Interest Expense Related

Debt - Interest Expense Related to 2024 Notes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Debt Instrument
Amortization of the debt discount and debt issuance costs			$ 29.1	$ 11.3
Convertible Debt | 2024 Notes
Debt Instrument
Contractual interest expense	$ 1.6	$ 0.5	3.2	0.7
Amortization of the debt discount and debt issuance costs	14.7	6.2	29.1	10.8
Total interest expense	$ 16.3	$ 6.7	$ 32.3	$ 11.5

Debt - Future Interest and Prin

Debt - Future Interest and Principal Payments (Details) $ in Millions	Dec. 26, 2020USD ($)
Debt Instrument
Remainder of 2021	$ 3.2
2022	6.4
2023	6.4
2024	456.4
2025	5.3
Thereafter	1,057.7
Total convertible notes payments	1,535.4
Convertible Debt | 2024 Notes
Debt Instrument
Remainder of 2021	0.6
2022	1.1
2023	1.1
2024	451.1
2025	0
Thereafter	0
Total convertible notes payments	453.9
Convertible Debt | 2026 Notes
Debt Instrument
Remainder of 2021	2.6
2022	5.3
2023	5.3
2024	5.3
2025	5.3
Thereafter	1,057.7
Total convertible notes payments	$ 1,081.5

Debt - Term Loan Facility Narra

Debt - Term Loan Facility Narrative (Details) - USD ($)	3 Months Ended	6 Months Ended
	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019	Dec. 31, 2018
Debt Instrument
Loss on early extinguishment of debt		$ 0	$ 8,000,000
Secured debt | Term loan
Debt Instrument
Principal				$ 500,000,000
Interest expense	$ 11,600,000		18,100,000
Loss on early extinguishment of debt	$ 8,000,000		$ 8,000,000

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Dec. 26, 2020	Sep. 26, 2020	Dec. 28, 2019	Sep. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	$ 1,816.1	$ 1,749.2	$ 1,561.3	$ 1,497.1	$ 1,749.2	$ 1,497.1
Other comprehensive loss	(0.4)	(1.5)	(0.2)	0.1	(1.9)	(0.1)
Balance at the end of the period	1,921.9	1,816.1	1,681.6	1,561.3	1,921.9	1,681.6
Unrealized gain on available-for-sale securities, tax	0.5
Total
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	6.4	7.9	7.2	7.1	7.9	7.1
Other comprehensive loss		(1.5)	(0.2)	0.1
Balance at the end of the period	6	6.4	7	7.2	6	7
Foreign currency translation adjustments, net of tax
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	9.7	9.7	9.7	9.7	9.7	9.7
Other comprehensive loss	0	0	0	0
Balance at the end of the period	9.7	9.7	9.7	9.7	9.7	9.7
Defined benefit obligations, net of tax
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	(4.2)	(4.2)	(3.5)	(3.5)	(4.2)	(3.5)
Other comprehensive loss	0	0	0	0
Balance at the end of the period	(4.2)	(4.2)	(3.5)	(3.5)	(4.2)	(3.5)
Unrealized gain (loss) on available-for-sale securities, net of tax
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	0.9	2.4	1	0.9	2.4	0.9
Other comprehensive loss	(0.4)	(1.5)	(0.2)	0.1
Balance at the end of the period	$ 0.5	$ 0.9	$ 0.8	$ 1	$ 0.5	$ 0.8

Restructuring and Related Cha_3

Restructuring and Related Charges - Summary of Activity of Restructuring and Related Charges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Summary of Restructuring Activity and Related Charges
Balance as of beginning of period	$ 4.4	$ 10.7	$ 5.2	$ 14.6
Charges	0.2	0.9	0.2	2.2
Payments	0	(6.6)	(0.8)	(11.8)
Balance as of end of period	$ 4.6	$ 5	$ 4.6	$ 5

Restructuring and Related Cha_4

Restructuring and Related Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Restructuring and Related Activities [Abstract]
Charges	$ 0.2	$ 0.9	$ 0.2	$ 2.2
Payments	$ 0	$ (6.6)	$ (0.8)	$ (11.8)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 14.9	$ 8.6	$ 31.4	$ 14.4
Discrete tax benefit, uncertain tax positions	2.5
Unrecognized tax benefit that would impact tax rate if recognized	27.6		27.6
Unrecognized tax benefit that could affect tax rate to decrease over next 12 months	$ 5.3		$ 5.3

Equity - Description of Lumentu

Equity - Description of Lumentum Stock-Based Benefit Plans Narrative (Details) - shares	6 Months Ended	12 Months Ended
	Dec. 26, 2020	Jun. 27, 2015	Jun. 27, 2020
Share-based Compensation Arrangement by Share-based Payment Award
Shares of common stock available for grant (in shares)	2,300,000		3,500,000
Full Value Awards
Share-based Compensation Arrangement by Share-based Payment Award
Stock options issued and outstanding (in shares)	2,300,000
Oclaro | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Shares unvested to restricted stock units (in shares)	200,000
2015 Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Shares of common stock available for grant (in shares)	2,300,000
2015 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period	3 years
2015 Plan | RSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period	1 year
2015 Plan | RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period	4 years
2015 Plan | PSUs
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period	3 years
2015 Purchase Plan | Employee stock
Share-based Compensation Arrangement by Share-based Payment Award
Shares of common stock available for grant (in shares)	1,700,000
Discount rate provided under purchase plan (as a percent)		15.00%
Look-back period		6 months
Common stock authorized for issuance under plan (in shares)		3,000,000

Equity - Stock-Based Compensati

Equity - Stock-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019	Jun. 27, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Stock-based compensation	$ 24.1	$ 20.2	$ 43.6	$ 36.9
Income tax benefit associated with stock-based compensation	3.6	3.8	8.8	6.6
Stock-based compensation capitalized to inventory			4.9		$ 3.6
Cost of sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Stock-based compensation	4.8	4.1	8.5	8.3
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Stock-based compensation	5.1	4.1	9.5	7.9
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount
Stock-based compensation	$ 14.2	$ 12	$ 25.6	$ 20.7

Equity - Stock Award Activity (

Equity - Stock Award Activity (Details) shares in Millions	6 Months Ended
	Dec. 26, 2020$ / sharesshares
Restricted Stock Units
Number of Shares
Unvested balance as of beginning of period (in shares) | shares	1.9
Granted (in shares) | shares	1.1
Vested (in shares) | shares	(0.8)
Canceled (in shares) | shares	(0.1)
Unvested balance as of end of period (in shares) | shares	2.1
Weighted-Average Grant Date Fair Value per Share
Balance at beginning of period (in usd per share) | $ / shares	$ 56.6
Granted (in usd per share) | $ / shares	86.7
Vested (in usd per share) | $ / shares	56.1
Canceled (in usd per share) | $ / shares	62.3
Balance at end of period (in usd per share) | $ / shares	$ 72.2
Performance Stock Units
Number of Shares
Unvested balance as of beginning of period (in shares) | shares	0.3
Granted (in shares) | shares	0.2
Vested (in shares) | shares	(0.1)
Canceled (in shares) | shares	0
Unvested balance as of end of period (in shares) | shares	0.4
Weighted-Average Grant Date Fair Value per Share
Balance at beginning of period (in usd per share) | $ / shares	$ 60.6
Granted (in usd per share) | $ / shares	86.7
Vested (in usd per share) | $ / shares	57.7
Canceled (in usd per share) | $ / shares	71.8
Balance at end of period (in usd per share) | $ / shares	$ 73.3

Equity - Stock Award Activity N

Equity - Stock Award Activity Narrative (Details) $ in Millions	6 Months Ended
	Dec. 26, 2020USD ($)
Equity [Abstract]
Stock-based compensation cost related to awards granted to employees	$ 168
Estimated amortization period	2 years

Equity - Awards Available for G

Equity - Awards Available for Grant (Details) shares in Millions	6 Months Ended
	Dec. 26, 2020shares
Awards Available for Grant
Balance as of beginning of period (in shares)	3.5
Granted (in shares)	(1.3)
Canceled (in shares)	0.1
Balance as of end of period (in shares)	2.3

Equity - Employee Stock Purchas

Equity - Employee Stock Purchase Plan Activity Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	$ 24.1	$ 20.2	$ 43.6	$ 36.9
2015 Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares issued to employees (in shares)	0.1		0.1
2015 Purchase Plan | Employee stock
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	$ 1.2	$ 0.8	$ 2.3	$ 1.7

Commitments and Contingencies -

Commitments and Contingencies - Purchase Obligations Narrative (Details) $ in Millions	6 Months Ended
	Dec. 26, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Legally-binding purchase commitment obligations	$ 219.8
Typical duration of supply agreements with single or limited source vendors	1 year

Commitments and Contingencies_2

Commitments and Contingencies - Product Warranties Narrative (Details)	6 Months Ended
	Dec. 26, 2020
Loss Contingencies
Product warranty term	12 months
Minimum
Loss Contingencies
Product warranty term	6 months
Maximum
Loss Contingencies
Product warranty term	5 years

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Changes in Warranty Reserve (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Changes in warranty reserve
Balance as of beginning of period	$ 7.6	$ 7	$ 5	$ 7.5
Provision for warranty	0.2	0.6	4.1	1.8
Utilization of reserve	(2.1)	(0.8)	(3.4)	(2.5)
Balance as of end of period	$ 5.7	$ 6.8	$ 5.7	$ 6.8

Commitments and Contingencies_4

Commitments and Contingencies - Merger Litigation (Details)	6 Months Ended
	Dec. 26, 2020lawsuit_filed
Oclaro
Business Acquisition
Number of lawsuits filed	7

Operating Segments and Geogra_3

Operating Segments and Geographic Information - Narrative (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020segmentregion	Dec. 28, 2019	Jun. 27, 2020
Concentration Risk
Number of operating segments			2
Number of reportable segments			2
Number of geographic regions | region			3
Inventory Purchases | Customer concentration risk | Two Vendors
Concentration Risk
Concentration risk, percentage	67.00%	87.00%	65.00%	78.00%
Two Customer | Revenue | Customer concentration risk
Concentration Risk
Concentration risk, percentage	45.00%	41.00%	45.00%	44.00%
Two Customer | Accounts Receivable | Customer concentration risk
Concentration Risk
Concentration risk, percentage			24.00%
One Customer | Accounts Receivable | Customer concentration risk
Concentration Risk
Concentration risk, percentage					14.00%

Operating Segments and Geogra_4

Operating Segments and Geographic Information - Schedule of Information on Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Information on reportable segments
Net revenue	$ 478.8	$ 457.8	$ 931.2	$ 907.7
Gross profit	229.6	189.1	435.3	356.8
Stock-based compensation	(24.1)	(20.2)	(43.6)	(36.9)
Amortization of acquired intangibles	(20.9)	(18.6)	(41.6)	(37.4)
Operating segments
Information on reportable segments
Net revenue	478.8	457.8	931.2	907.7
Gross profit	255.9	216.8	491.1	422.9
Operating segments | OpComms
Information on reportable segments
Net revenue	449.1	409.4	877.6	825.5
Gross profit	241.8	196.4	466.6	388.3
Operating segments | Lasers
Information on reportable segments
Net revenue	29.7	48.4	53.6	82.2
Gross profit	14.1	20.4	24.5	34.6
Unallocated corporate items:
Information on reportable segments
Stock-based compensation	(4.8)	(4.1)	(8.5)	(8.3)
Amortization of acquired intangibles	(15)	(12.4)	(30)	(24.9)
Amortization of inventory fair value adjustments	0	(2.1)	0	(4.3)
Inventory and fixed asset write down due to product line exits	(0.1)	(2.6)	(0.4)	(3.7)
Integration related costs	0	0	0	(3.4)
Other charges	(6.4)	(6.5)	(16.9)	(21.5)
Unallocated corporate items: | Fiber Laser
Information on reportable segments
Impairment charges	4.6
Unallocated corporate items: | Thailand
Information on reportable segments
Other charges	(0.4)	(2)	(2.5)	(8.1)
Unallocated corporate items: | Huawei
Information on reportable segments
Other charges	$ (0.8)	$ (6)	$ (6.7)	$ (12.7)

Operating Segments and Geogra_5

Operating Segments and Geographic Information - Schedule of Percentage of Total Net Revenue Attributable to Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Concentration Risk
Net revenue	$ 478.8	$ 457.8	$ 931.2	$ 907.7
Product offerings | OpComms
Concentration Risk
Net revenue	449.1	409.4	877.6	825.5
Product offerings | OpComms | Telecom and Datacom
Concentration Risk
Net revenue	286.2	266.3	547.5	514.4
Product offerings | OpComms | Consumer and Industrial
Concentration Risk
Net revenue	162.9	143.1	330.1	311.1
Product offerings | Lasers
Concentration Risk
Net revenue	$ 29.7	$ 48.4	$ 53.6	$ 82.2
Product offerings | Revenue | OpComms
Concentration Risk
Concentration risk, percentage	93.80%	89.40%	94.20%	90.90%
Product offerings | Revenue | OpComms | Telecom and Datacom
Concentration Risk
Concentration risk, percentage	59.80%	58.20%	58.80%	56.60%
Product offerings | Revenue | OpComms | Consumer and Industrial
Concentration Risk
Concentration risk, percentage	34.00%	31.20%	35.40%	34.30%
Product offerings | Revenue | Lasers
Concentration Risk
Concentration risk, percentage	6.20%	10.60%	5.80%	9.10%

Operating Segments and Geogra_6

Operating Segments and Geographic Information - Schedule of Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019
Net revenue and identifiable assets by geographic regions
Amount	$ 478.8	$ 457.8	$ 931.2	$ 907.7
Americas | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 95	$ 70.3	$ 157.9	$ 137.2
% of Total	19.80%	15.40%	17.00%	15.10%
United States | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 39.7	$ 43.4	$ 60	$ 80.3
% of Total	8.30%	9.50%	6.40%	8.80%
Mexico | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 51.3	$ 26.2	$ 91.1	$ 55.1
% of Total	10.70%	5.70%	9.80%	6.10%
Other Americas | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 4	$ 0.7	$ 6.8	$ 1.8
% of Total	0.80%	0.20%	0.80%	0.20%
Asia Pacific | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 348.6	$ 350.4	$ 703.4	$ 701.1
% of Total	72.80%	76.60%	75.50%	77.30%
Hong Kong | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 148	$ 144.5	$ 292.4	$ 278.3
% of Total	30.90%	31.60%	31.40%	30.70%
Philippines | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 40.6	$ 4.8	$ 103.4	$ 29.8
% of Total	8.50%	1.00%	11.10%	3.30%
South Korea | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 66	$ 85	$ 122	$ 176.6
% of Total	13.80%	18.60%	13.10%	19.50%
Other Asia-Pacific | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 94	$ 116.1	$ 185.6	$ 216.4
% of Total	19.60%	25.40%	19.90%	23.80%
EMEA | Geographic Concentration Risk | Total Net Revenue
Net revenue and identifiable assets by geographic regions
Amount	$ 35.2	$ 37.1	$ 69.9	$ 69.4
% of Total	7.40%	8.00%	7.50%	7.60%

Operating Segments and Geogra_7

Operating Segments and Geographic Information - Schedule of Performance Obligations (Details) $ in Millions	Dec. 26, 2020USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Performance obligations	$ 477.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-12-27
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Performance obligations	$ 475.4
Performance obligation period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-06-27
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Performance obligations	$ 2.4
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-06-26
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Performance obligations	$ 0
Performance obligation period	1 year

Operating Segments and Geogra_8

Operating Segments and Geographic Information - Schedule of Contract Balances (Details) $ in Millions	6 Months Ended
	Dec. 26, 2020USD ($)
Accounts receivable, net
Accounts receivable, net, beginning balance	$ 233.5
Accounts receivable, net, change	43.2
Accounts receivable, net, ending balance	$ 276.7
Accounts receivable, net, percentage change	18.50%
Deferred revenue and customer deposits
Deferred revenue and customer deposits, beginning balance	$ 1.9
Deferred revenue and customer deposits, change	(1.4)
Deferred revenue and customer deposits, ending balance	$ 0.5
Deferred revenue and customer deposits, percentage change	(73.70%)

Operating Segments and Geogra_9

Operating Segments and Geographic Information - Schedule of Long-lived Assets by Geographic Region (Details) - USD ($) $ in Millions	Dec. 26, 2020	Jun. 27, 2020
Property, plant and equipment, net
Total long-lived assets	$ 385.8	$ 393
United States
Property, plant and equipment, net
Total long-lived assets	138.6	139.1
Thailand
Property, plant and equipment, net
Total long-lived assets	112.1	122.6
China
Property, plant and equipment, net
Total long-lived assets	42.5	43.2
Japan
Property, plant and equipment, net
Total long-lived assets	34.5	32.3
Other countries
Property, plant and equipment, net
Total long-lived assets	$ 58.1	$ 55.8

Subsequent Event - (Details)

Subsequent Event - (Details) - USD ($)	Jan. 18, 2021	Dec. 31, 2018
Term loan | Secured debt
Subsequent Event
Principal		$ 500,000,000
Subsequent Event | Plan
Subsequent Event
Contract termination fee	$ 337,700,000
Subsequent Event | Plan | Anti-trust Approval
Subsequent Event
Contract termination fee	279,000,000
Subsequent Event | Plan | Term loan | Secured debt
Subsequent Event
Principal	2,100,000,000
Subsequent Event | Plan | Coherent
Subsequent Event
Contract termination fee	$ 217,600,000
Subsequent Event | Plan | Coherent | Surviving Entity After Merger
Subsequent Event
Percentage of coherent outstanding common stock acquired	27.00%
Subsequent Event | Plan | Coherent
Subsequent Event
Price per share of the coherent common stock acquired (in dollars per share)	$ 100
Number of outstanding shares of coherent common stock acquired (in shares)	1.1851
Total consideration	$ 5,700,000,000
Issuance of common stock	3,200,000,000
Consideration transferred in new debt	$ 2,100,000,000