Applied Optoelectronics (AAOI) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Document Information [Line Items]
Entity Central Index Key	0001158114
Entity Registrant Name	APPLIED OPTOELECTRONICS, INC.
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2021
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-36083
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	76-0533927
Entity Address, Address Line One	13139 Jess Pirtle Blvd.
Entity Address, City or Town	Sugar Land
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77478
City Area Code	281
Local Phone Number	295-1800
Title of 12(b) Security	Common Stock, Par value $0.001
Trading Symbol	AAOI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		26,862,088

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 45,482	$ 43,425
Restricted cash	3,856	6,689
Accounts receivable - trade, net of allowance of $62 and $62, respectively	47,570	43,042
Notes receivable	1,440	401
Inventories	106,336	110,397
Prepaid income tax	2	2
Prepaid expenses and other current assets	5,169	5,213
Total current assets	209,855	209,169
Property, plant and equipment, net	248,303	252,984
Land use rights, net	5,780	5,854
Operating right of use asset	7,486	7,729
Financing right of use asset	80	88
Intangible assets, net	3,943	3,999
Other assets, net	915	982
TOTAL ASSETS	476,362	480,805
Current liabilities
Current portion of notes payable and long-term debt	50,803	38,265
Accounts payable	26,201	29,482
Bank acceptance payable	6,344	15,860
Current lease liability - operating	1,021	1,012
Current lease liability - financing	18	18
Accrued liabilities	14,028	18,511
Total current liabilities	98,415	103,148
Notes payable and long-term debt, less current portion	13,686	13,904
Convertible senior notes	78,058	77,854
Non-current lease liability - operating	7,654	7,926
Non-current lease liability - financing	77	82
TOTAL LIABILITIES	197,890	202,914
Stockholders' equity:
Preferred Stock; 5,000 shares authorized at $0.001 par value; no shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	0	0
Common Stock; 45,000 shares authorized at $0.001 par value; 26,787 and 25,110 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	27	25
Additional paid-in capital	371,920	354,685
Accumulated other comprehensive income	10,656	11,690
Accumulated deficit	(104,131)	(88,509)
TOTAL STOCKHOLDERS' EQUITY	278,472	277,891
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 476,362	$ 480,805

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts receivable, allowance	$ 62	$ 62
Preferred stock, shares authorized (in shares)	5,000	5,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, shares authorized (in shares)	45,000	45,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares issued (in shares)	26,787	25,110
Common stock, shares outstanding (in shares)	26,787	25,110

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue, net	$ 49,701	$ 40,467
Cost of goods sold	38,982	34,129
Gross profit	10,719	6,338
Operating expenses
Research and development	10,928	10,558
Sales and marketing	2,960	2,936
General and administrative	10,869	10,638
Total operating expenses	24,757	24,132
Loss from operations	(14,038)	(17,794)
Other income (expense)
Interest income	16	147
Interest expense	(1,431)	(1,455)
Other income (expense), net	(169)	256
Total other income (expense), net	(1,584)	(1,052)
Loss before income taxes	(15,622)	(18,846)
Income tax benefit	0	2,049
Net loss	$ (15,622)	$ (16,797)
Net loss per share
Basic (in dollars per share)	$ (0.59)	$ (0.83)
Diluted (in dollars per share)	$ (0.59)	$ (0.83)
Weighted average shares used to compute net loss per share:
Basic (in shares)	26,438,071	20,208,383
Diluted (in shares)	26,438,071	20,208,383

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net loss	$ (15,622)	$ (16,797)
Loss on foreign currency translation adjustment	(1,034)	(2,402)
Comprehensive loss	$ (16,656)	$ (19,199)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2019	0	20,140
Balance at Dec. 31, 2019	$ 0	$ 20	$ 303,401	$ 430	$ (30,057)	$ 273,794
Public offering of common stock, net (in shares)	0	4
Public offering of common stock, net	$ 0	$ 0	75	0	0	75
Issuance of restricted stock, net of shares withheld for employee tax (in shares)	0	105
Issuance of restricted stock, net of shares withheld for employee tax	$ 0	$ 0	(259)	0	0	(259)
Share-based compensation	0	0	3,238	0	0	3,238
Foreign currency translation adjustment	0	0	0	(2,402)	0	(2,402)
Net loss	0	0	0	0	(16,797)	(16,797)
Public offering of common stock, net	$ 0	$ 0	(75)	0	0	(75)
Balance (in shares) at Mar. 31, 2020	0	20,249
Balance at Mar. 31, 2020	$ 0	$ 20	306,305	(1,972)	(46,854)	257,499
Balance (in shares) at Dec. 31, 2020	0	25,110
Balance at Dec. 31, 2020	$ 0	$ 25	354,685	11,690	(88,509)	277,891
Public offering of common stock, net (in shares)	0	1,511
Public offering of common stock, net	$ 0	$ 2	14,966	0	0	$ 14,968
Stock options exercised, net of shares withheld for employee tax (in shares)	0	2				2
Stock options exercised, net of shares withheld for employee tax	$ 0	$ 0	8	0	0	$ 8
Issuance of restricted stock, net of shares withheld for employee tax (in shares)	0	164
Issuance of restricted stock, net of shares withheld for employee tax	$ 0	$ 0	(258)	0	0	(258)
Share-based compensation	0	0	2,519	0	0	2,519
Foreign currency translation adjustment	0	0	0	(1,034)	0	(1,034)
Net loss	0	0	0	0	(15,622)	(15,622)
Public offering of common stock, net	$ 0	$ (2)	(14,966)	0	0	(14,968)
Balance (in shares) at Mar. 31, 2021	0	26,787
Balance at Mar. 31, 2021	$ 0	$ 27	$ 371,920	$ 10,656	$ (104,131)	$ 278,472

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Net loss	$ (15,622)	$ (16,797)
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for losses on accounts receivable	0	35
Lower of cost or market reserve adjustment to inventory	937	1,648
Depreciation and amortization	6,444	6,031
Amortization of debt issuance costs	221	220
Deferred income taxes, net	0	(1,877)
Share-based compensation	2,519	3,238
Unrealized foreign exchange gain	850	(103)
Changes in operating assets and liabilities:
Accounts receivable, trade	(4,528)	8,836
Notes receivable	(1,055)	0
Prepaid income tax	0	(151)
Inventories	2,844	(4,533)
Other current assets	(76)	(1,085)
Operating right of use asset	230	63
Accounts payable	(3,281)	3,408
Accrued liabilities	(4,449)	(7,117)
Lease liability	(248)	(62)
Net cash used in operating activities	(15,214)	(8,246)
Investing activities:
Purchase of property, plant and equipment	(2,212)	(2,787)
Proceeds from disposal of equipment	0	52
Deposits and prepaid for equipment	(115)	(353)
Purchase of intangible assets	(95)	(112)
Net cash used in investing activities	(2,422)	(3,200)
Financing activities:
Principal payments of long-term debt and notes payable	(1,029)	(1,108)
Proceeds from line of credit borrowings	39,512	24,916
Repayments of line of credit borrowings	(26,320)	(20,000)
Proceeds from bank acceptance payable	4,772	7,195
Repayments of bank acceptance payable	(14,280)	(3,798)
Proceeds from issuance of convertible senior notes, net of debt issuance costs	0	(13)
Principal payments of financing lease	(4)	(4)
Exercise of stock options	8	0
Payments of tax withholding on behalf of employees related to share-based compensation	(258)	(259)
Proceeds from common stock offering, net	15,074	(75)
Net cash provided by financing activities	17,475	6,854
Effect of exchange rate changes on cash	(615)	81
Net decrease in cash, cash equivalents and restricted cash	(776)	(4,511)
Cash, cash equivalents and restricted cash at beginning of period	50,114	67,028
Cash, cash equivalents and restricted cash at end of period	49,338	62,517
Supplemental disclosure of cash flow information:
Interest, net of amounts capitalized	2,219	2,237
Income taxes	0	(21)
Non-cash investing and financing activities:
Net change in accounts payable related to property and equipment additions	(506)	75
Net change in deposits and prepaid for equipment related to property and equipment additions	$ 47	$ 304

Note 1 - Description of Busines

Note 1 - Description of Business	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Business Description and Basis of Presentation [Text Block]	Note 1. ​ Business Overview ​ Applied Optoelectronics, Inc. (“AOI” or the “Company”) is a Delaware corporation. The Company is a leading, vertically integrated provider of fiber-optic networking products, primarily for four ​ The Company has manufacturing and research and development facilities located in the U.S., Taiwan and China. In the U.S., at its corporate headquarters and manufacturing facilities in Sugar Land, Texas, the Company primarily manufactures lasers and laser components and performs research and development activities for laser component and optical module products. In addition, the Company also has a research and development facility in Duluth, Georgia. The Company operates in Taipei, Taiwan and Ningbo, China through its wholly-owned subsidiary Prime World International Holdings, Ltd. (“Prime World”, incorporated in the British Virgin Islands). Prime World operates a branch in Taipei, Taiwan, which primarily manufactures transceivers and performs research and development activities for the transceiver products. Prime World is also the parent of Global Technology, Inc. (“Global”, incorporated in the People’s Republic of China). Through Global, the Company primarily manufactures certain of its data center transceiver products, including subassemblies, as well as CATV systems and equipment, and performs research and development activities for the CATV products. ​ Interim Financial Statements ​ The unaudited condensed consolidated financial statements of the Company as of March 31, 2021 December 31, 2020 three March 31, 2021 March 31, 2020 10 10 01 X 10 December 31, 2020 three March 31, 2021 not ​ Use of Estimates ​ The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported. Actual results could differ from those estimates in the consolidated financial statements and accompanying notes. Significant estimates and assumptions that impact these financial statements and the accompanying notes relate to, among other things, allowance for credit losses, inventory reserve, product warranty costs, share-based compensation expense, estimated useful lives of property and equipment, and taxes. ​

Note 2 - Significant Accounting

Note 2 - Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Significant Accounting Policies [Text Block]	Note 2. ​ There have been no three March 31, 2021 2020 ​ Recent Accounting Pronouncements ​ ​ Recent Accounting Pronouncements Yet to be Adopted In March 2020, 2020 04, 848 2020 04 January 2021 2021 01, 2020 04 2021 01 December 31, 2022 2020 04 2021 01 may March 31, 2021, not may In August 2020, 2020 06, 470 20 815 40 two three 470 20 December 15, 2021. In November 2020, 301 302 303 January 11, 2021, thirty February 10, 2021, first 210 not

Note 3 - Revenue Recognition

Note 3 - Revenue Recognition	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Revenue from Contract with Customer [Text Block]	Note 3. ​ ​ Disaggregation of Revenue ​ Revenue is classified based on the location where the product is manufactured. For additional information on the disaggregated revenues by geographical region, see Note 17, ​ Revenue is also classified by major product category and is presented below (in thousands): ​ Three months ended March 31, ​ % of % of ​ 2021 Revenue 2020 Revenue Data Center $ 25,939 52.2 % $ 33,264 82.2 % CATV 18,638 37.5 % 4,223 10.4 % Telecom 4,479 9.0 % 2,560 6.3 % FTTH 423 0.9 % - 0.0 % Other 222 0.4 % 420 1.0 % Total Revenue $ 49,701 100.0 % $ 40,467 100.0 % ​ ​

Note 4 - Leases

Note 4 - Leases	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Lessee, Operating and Finance Leases [Text Block]	Note 4. ​ The Company leases space under non-cancellable operating leases for manufacturing facilities, research and development offices and certain storage facilities and apartments. These leases do not one one ​ As most of the Company’s leases do not ​ The Components of lease expense were as follows for the periods indicated (in thousands): Three months ended March 31, ​ 2021 2020 Operating lease expense $ 303 $ 295 Financing lease expense 8 8 Short Term lease expense 9 21 Total lease expense $ 320 $ 324 Maturities of lease liabilities are as follows for the future one March 31, 2021 ​ Operating Financing 2022 $ 1,335 $ 22 2023 1,328 22 2024 1,247 60 2025 1,249 — 2026 1,278 — 2027 and thereafter 3,892 — Total lease payments $ 10,329 $ 104 Less imputed interest (1,654 ) (9 ) Present value $ 8,675 $ 95 ​ The weighted average remaining lease term and discount rate for operating leases were as follows for the periods indicated: ​ March 31, ​ 2021 2020 Weighted Average Remaining Lease Term (Years) - operating leases 7.84 8.87 Weighted Average Remaining Lease Term (Years) - financing leases 2.58 3.57 Weighted Average Discount Rate - operating leases 3.23 % 3.17 % Weighted Average Discount Rate - financing leases 5.00 % 5.00 % Supplemental cash flow information related to operating leases was as follows for the periods indicated (in thousands): Three months ended March 31, ​ 2021 2020 Cash paid for amounts included in the measurement of lease liabilities ​ ​ Operating cash flows from operating leases 330 318 Operating cash flows from financing lease 1 1 Financing cash flows from financing lease 4 4 Right-of-use assets obtained in exchange for new operating lease liabilities 0 261 ​

Note 5 - Cash, Cash Equivalents

Note 5 - Cash, Cash Equivalents and Restricted Cash	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Cash and Cash Equivalents Disclosure [Text Block]	Note 5. ​ The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the statement of financial position that sum to the total of the same such amounts in the statement of cash flows (in thousands): March 31, December 31, ​ 2021 2020 Cash and cash equivalents $ 45,482 $ 43,425 Restricted cash 3,856 6,689 Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 49,338 $ 50,114 ​ Restricted cash includes guarantee deposits for customs duties, China government subsidy fund, and compensating balances required for certain credit facilities. As of March 31, 2021 December 31, 2020, March 31, 2021 December 31, 2020 ​

Note 6 - Earnings (Loss) Per Sh

Note 6 - Earnings (Loss) Per Share	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Earnings Per Share [Text Block]	Note 6. ​ Basic net loss per share has been computed using the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share has been computed using the weighted-average number of shares of common stock and dilutive potential common shares from stock options, restricted stock units and senior convertible notes outstanding during the period. In periods with net losses, normally dilutive shares become anti-dilutive. Therefore, basic and diluted loss per share are the same. ​ The following table sets forth the computation of the basic and diluted net loss per share for the periods indicated (in thousands): ​ Three months ended March 31, ​ 2021 2020 Numerator: ​ ​ Net loss $ (15,622 ) $ (16,797 ) Denominator: ​ ​ Weighted average shares used to compute net loss per share ​ ​ Basic 26,438 20,208 Diluted 26,438 20,208 Net loss per share ​ ​ Basic $ (0.59 ) $ (0.83 ) Diluted $ (0.59 ) $ (0.83 ) ​ The following potentially dilutive securities were excluded from the diluted net loss per share as their effect would have been antidilutive (in thousands): ​ Three months ended March 31, ​ 2021 2020 Employee stock options 13 26 Restricted stock units 20 22 Shares for convertible senior notes 4,587 4,587 Total antidilutive shares 4,620 4,635 ​

Note 7 - Inventories

Note 7 - Inventories	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Inventory Disclosure [Text Block]	Note 7. ​ Inventories, net of inventory write-downs, consist of the following for the periods indicated (in thousands): ​ ​ March 31, 2021 December 31, 2020 Raw materials $ 28,304 $ 25,555 Work in process and sub-assemblies 49,194 52,544 Finished goods 28,838 32,298 Total inventories $ 106,336 $ 110,397 ​ The lower of cost or market adjustment expensed for inventory for the three March 31, 2021 2020 For the three March 31, 2021 2020 ​

Note 8 - Property, Plant and Eq

Note 8 - Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Property, Plant and Equipment Disclosure [Text Block]	Note 8. ​ Property, plant and equipment consisted of the following for the periods indicated (in thousands): ​ ​ March 31, 2021 December 31, 2020 Land improvements $ 806 $ 806 Building and improvements 88,194 88,280 Machinery and equipment 255,530 253,738 Furniture and fixtures 5,520 5,540 Computer equipment and software 12,005 11,912 Transportation equipment 696 699 ​ 362,751 360,975 Less accumulated depreciation and amortization (148,029 ) (142,434 ) ​ 214,722 218,541 Construction in progress 32,480 33,342 Land 1,101 1,101 Total property, plant and equipment, net $ 248,303 $ 252,984 ​ For the three March 31, 2021 2020 three March 31, 2021 2020 As of March 31, 2021 , the Company concluded that its continued loss history constitutes a triggering event as described in ASC 360 - 10 - 35 - 21, Property, Plant, and Equipment . The Company performed a recoverability test and concluded that future undiscounted cash flows exceed the carrying amount of the Company’s long-lived assets and therefore no

Note 9 - Intangible Assets, Net

Note 9 - Intangible Assets, Net	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Intangible Assets Disclosure [Text Block]	Note 9. ​ Intangible assets consisted of the following for the periods indicated (in thousands): ​ March 31, 2021 ​ Gross Accumulated Intangible ​ Amount amortization assets, net Patents $ 8,251 $ (4,314 ) $ 3,937 Trademarks 22 (16 ) 6 Total intangible assets $ 8,273 $ (4,330 ) $ 3,943 ​ December 31, 2020 ​ Gross Accumulated Intangible ​ Amount amortization assets, net Patents $ 8,158 $ (4,165 ) $ 3,993 Trademarks 21 (15 ) 6 Total intangible assets $ 8,179 $ (4,180 ) $ 3,999 ​ For the three March 31, 2021 2020 At March 31, 2021 2022 $ 588 2023 588 2024 588 2025 588 2026 588 thereafter 1,003 $ 3,943

Note 10 - Fair Value of Financi

Note 10 - Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Fair Value Disclosures [Text Block]	Note 10. ​ The following table represents a summary of the Company’s financial instruments measured at fair value on a recurring basis for the periods indicated (in thousands): ​ As of March 31, 2021 As of December 31, 2020 ​ (Level 1) (Level 2) (Level 3) Total (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents $ 45,482 $ — $ — $ 45,482 $ 43,425 $ — $ — $ 43,425 Restricted cash 3,856 — — 3,856 $ 6,689 — — 6,689 Total assets $ 49,338 $ — $ — $ 49,338 $ 50,114 $ — $ — $ 50,114 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ Bank acceptance payable $ — $ 6,344 $ — $ 6,344 $ — $ 15,860 $ — 15,860 Convertible senior notes — 70,526 — 70,526 — 70,225 — 70,225 Total liabilities $ — $ 76,870 $ — $ 76,870 $ — $ 86,085 $ — $ 86,085 ​ The carrying value amounts of accounts receivable, note receivable, prepaid expenses and other current assets, accounts payable, accrued expenses and other current liabilities approximate fair value because of the short-term maturity of these instruments. The carrying value amounts of bank acceptances approximate fair value due to the short-term nature of the debt since it renews frequently at current interest rates. The Company believes that the interest rates in effect at each period end represent the current market rates for similar borrowings. The fair value of its convertible senior debt is measured for disclosure purpose. The fair value is based on observable market prices for this debt, which is traded in less active markets and are therefore classified as a Level 2 ​

Note 11 - Notes Payable and Lon

Note 11 - Notes Payable and Long-term Debt	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Debt Disclosure [Text Block]	Note 11. ​ Notes payable and long-term debt consisted of the following for the periods indicated (in thousands): ​ March 31, 2021 December 31, 2020 Revolving line of credit with a U.S. bank up to $20,000 with interest at LIBOR plus 1.5% , maturing April 2, 2021 $ 18,700 $ 18,700 Paycheck Protection Program Term Note with interest at fixed rate 1.0%, maturing April 16, 2022 6,229 6,229 Revolving line of credit with a Taiwan bank up to $3,436 with 2.2% interest, maturing April 14, 2021 1,752 1,756 Notes payable to a finance company due in monthly installments with 3.5% interest, maturing January 21, 2022 1,410 1,941 Notes payable to a finance company due in monthly installments with 3.1% interest, maturing January 21, 2022 1,650 2,149 Revolving line of credit with a China bank up to $8,917 with interest ranging from 4.5%, maturing October 14, 2020 — 2,299 Revolving line of credit with a China bank up to $25,449 with interest from 3.01% to 4.57%, maturing May 24, 2024 15,785 11,603 Credit facility with a China bank up to $14,125 with interest of 3.5%, maturing January 5, 2024 11,506 — Credit facility with a China bank up to $7,167 with interest of 5.7%, maturing from June 20, 2022 7,457 7,510 Sub-total 64,489 52,187 Less debt issuance costs, net - (18 ) Grand total 64,489 52,169 Less current portion (50,803 ) (38,265 ) Non-current portion $ 13,686 $ 13,904 ​ ​ ​ Bank Acceptance Notes Payable ​ ​ Bank acceptance notes issued to vendors with a zero percent interest rate $ 6,344 $ 15,860 The current portion of long-term debt is the amount payable within one March 31, 2021 ​ Maturities of long-term debt are as follows for the future one March 31, ​ 2022 $ 50,803 2023 13,686 Total outstanding $ 64,489 ​ On September 28, 2017, December 2019). three not one ​ On March 30, 2018, $60 $26 $21.5 three $50 September 28, 2017. 1 three $50 2 five 3 seventy one one one not ​ On February 1, 2019, September 28, 2017, first March 30, 2018, three five seventy March 30, 2019 March 31, 2021 ​ On March 5, 2019, 12 $60,000,000 $25,000,000; not not not seven seven ​ On March 5, 2019, ​ On September 30, 2019, $25,000,000 $20,000,000; September 28, 2020 April 2, 2021; ( 1.0, twelve seventy-five ​ As of March 31, 2021 March 31, 2021 On April 17, 2020, 1.00%, first six November 2020, 18 April 2022. may September 14, 2020 not ​ On November 29, 2018, NT$267,340,468, three NT$67,340,468, NT$5,571,229, NT$6,139,188, NT$210,601,605, March 31, 2021 On January 21, 2019, NT$267,333,186, three NT$67,333,186, NT$5,570,167, NT$6,082,131, NT$209,555,736 March 31, 2021 ​ On September 15, 2020, November 29, 2018 January 21, 2019 ( NT$ 22,311,381 not NT$159,027,448, September 21, 2020 January 21, 2022, not On July 23, 2019, one NT$100 $3.3 “NT$100M “US$1M NT$100M US$1M NT$100M US$1M July 20, 2020, NT$100M three 3 October 16, 2020. NT$100M 90 120 US$1M NT$100M US$1M October 7, 2020. On October 7, 2020, NT$100 $3.44 NT$100M US$1M NT$100M US$1M NT$100M US$1M January 14, 2021, NT$100M three 3 April 14, 2021. may October 7, 2020 April 14, 2021. NT$100M US$1M March 31, 2021 On April 19, 2019, twelve April 14, 2020, six 6 may April 19, 2019 October 14, 2020 ( may may October 19, 2020 . On May 24, 2019, five 180 30 May 7, 2019; 9.9 April 30, 2019 $2 May 8, 2019. may 5 may March 31, 2021 ​ On June 21, 2019, “¥ 100 ¥100M January 6, 2021, ¥100M three 3 January 5, 2024. may ¥100M June 21, 2019 January 5, 2024 ( “¥100M ¥100M may ¥100M ¥100M may ¥100M ¥100M March 31, 2021 ¥100M ​ On June 21, 2019, three “¥50M ¥50M may ¥50M June 21, 2019 June 20, 2022 ( “¥50M ¥50M may ¥50M ¥50M may ¥50M March 31, 2021 ¥50M On October 19, 2020 , twelve 12 may October 16, 2020 October 15, 2021. may may March 31, 2021 ​ As of March 31, 2021 December 31, 2020 ​ One-month LIBOR rates were 0.11% and 0.14% on March 31, 2021 December 31, 2020 ​ As of March 31, 2021 December 31, 2020 ​

Note 12 - Convertible Senior No

Note 12 - Convertible Senior Notes	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Convertible Debt [Text Block]	Note 12. ​ On March 5, 2019, 2024 March 5, 2019 5.00% March 15 September 15 September 15, 2019. March 15, 2024, ​ The sale of the Notes generated net proceeds of $76.4 million, after deducting the Initial Purchasers’ discounts and offering expenses payable by the Company. The Company used approximately $37.8 million of the net proceeds from the offering to fully repay the CapEx Loan and Term Loan with Truist Bank and the remainder will be used for general corporate purposes. ​ The following table presents the carrying value of the Notes for the periods indicated (in thousands): ​ March 31, December 31, ​ 2021 2020 Principal $ 80,500 $ 80,500 Unamortized debt issuance costs (2,442 ) (2,646 ) Net carrying amount $ 78,058 $ 77,854 ​ The Notes are convertible at the option of holders of the Notes at any time until the close of business on the scheduled trading day immediately preceding the maturity date. Upon conversion, holders of the Notes will receive shares of the Company’s common stock, together, if applicable, with cash in lieu of any fractional share, at the then-applicable conversion rate. The initial conversion rate is 56.9801 shares of the Company’s common stock per $1,000 principal amount of Notes (representing an initial conversion price of approximately $17.55 per share of common stock, which represents an initial conversion premium of approximately 30% above the closing price of $13.50 per share of the Company’s common stock on February 28, 2019 March 15, 2022, Initially there are no Holders may The Company may not March 15, 2022. March 15, 2022, may not The Indenture contains covenants that limit the Company’s ability and the ability of our subsidiaries to, among other things: (i) incur or guarantee additional indebtedness or issue disqualified stock; and (ii) create or incur liens. ​ Pursuant to the guidance in ASC 815 40, Contracts in Entity’s Own Equity 815 40, 1 2 815 40 25 7 815 40 25 10. not 470 20, Debt with Conversion and Other Options The Company incurred approximately $4.1 million in transaction costs in connection with the issuance of the Notes. These costs were recognized as a reduction of the carrying amount of the Notes utilizing the effective interest method and are being amortized over the term of the notes. ​ The following table sets forth interest expense information related to the Notes (in thousands): ​ Three months ended March 31, ​ 2021 2020 Contractual interest expense $ 1,006 $ 1,006 Amortization of debt issuance costs 204 208 Total interest cost $ 1,210 $ 1,214 Effective interest rate 5.1 % 5.1 % ​

Note 13 - Accrued Liabilities

Note 13 - Accrued Liabilities	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	Note 13. ​ Accrued liabilities consisted of the following for the periods indicated (in thousands): ​ March 31, 2021 December 31, 2020 Accrued payroll $ 6,963 $ 10,517 Accrued employee benefits 2,871 3,057 Accrued state and local taxes 722 251 Accrued interest 297 1,256 Advance payments 566 303 Accrued product warranty 502 703 Accrued commission expenses 1,157 974 Accrued professional fees 281 377 Accrued shipping and tariff expenses 48 526 Accrued other 622 547 Total accrued liabilities $ 14,028 $ 18,511 ​ ​

Note 14 - Other Income and Expe

Note 14 - Other Income and Expense	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Other Nonoperating Income and Expense [Text Block]	Note 14. ​ Other income and (expense) consisted of the following for the periods indicated (in thousands): ​ Three months ended March 31, ​ 2021 2020 Foreign exchange transaction (loss) gain $ (208 ) $ 139 Government subsidy income 38 105 Other non-operating gain (loss) 1 12 Total other income (expense), net $ (169 ) $ 256 ​

Note 15 - Share-based Compensat

Note 15 - Share-based Compensation	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	Note 15. ​ Equity Plans ​ The Company’s board of directors and stockholders approved the following equity plans: ​ ● the 2006 ● the 2013 “2013 ​ The Company issued stock options, restricted stock awards (“RSAs”) and restricted stock units (“RSUs”) to employees, consultants and non-employee directors. Stock option awards generally vest over a four ten may September 2013, third ​ Stock Options ​ Options have been granted to the Company’s employees under the two first ten ​ The following is a summary of option activity (in thousands, except per share data): ​ ​ ​ Weighted ​ Weighted ​ ​ ​ Weighted Average ​ Average ​ ​ ​ Average Share Price Weighted Remaining Aggregate ​ Number of Exercise on Date of Average Contractual Intrinsic ​ shares Price Exercise Fair Value Life Value ​ (in thousands, except price data) Outstanding at January 1, 2021 276 $ 10.29 ​ $ 5.41 2.67 $ 54 Exercised (2 ) 6.00 — ​ 7 Forfeited (1 ) 6.00 ​ — Outstanding, March 31, 2021 273 $ 10.32 ​ $ 5.44 2.44 43 Exercisable, March 31, 2021 273 $ 10.32 ​ ​ 2.44 43 Vested and expected to vest 273 $ 10.33 ​ ​ 2.44 43 ​ As of March 31, 2021 ​ Restricted Stock Units/Awards ​ The following is a summary of RSU/RSA activity (in thousands, except per share data): ​ ​ Weighted ​ ​ ​ ​ Average Share Weighted Aggregate ​ Number of Price on Date Average Fair Intrinsic ​ shares of Release Value Value ​ (in thousands, except price data) Outstanding at January 1, 2021 1,325 ​ $ 14.97 $ 11,279 Granted 231 ​ 12.3 2,843 Released (189 ) $ 10.23 19.89 1,931 Cancelled/Forfeited (28 ) ​ 13.56 232 Outstanding, March 31, 2021 1,340 ​ 13.84 11,202 Vested and expected to vest 1,340 ​ 13.84 11,202 ​ As of March 31, 2021 ​ Share-Based Compensation ​ Employee share-based compensation expenses recognized for the periods indicated (in thousands): ​ Three months ended ​ March 31, ​ 2021 2020 Share-based compensation - by expense type ​ ​ Cost of goods sold $ 201 $ 246 Research and development 563 688 Sales and marketing 219 291 General and administrative 1,536 2,013 Total share-based compensation expense $ 2,519 $ 3,238

Note 16 - Income Taxes

Note 16 - Income Taxes	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Income Tax Disclosure [Text Block]	Note 16. ​ The Company’s effective tax rate for the three March 31, 2021 2020 three March 31, 2021, three March 31, 2020, The Company continually monitors and performs an assessment of the realizability of its DTAs, including an analysis of factors such as future taxable income, reversal of existing taxable temporary differences, and tax planning strategies. In assessing the need for a valuation allowance, the Company considered both positive and negative evidence related to the likelihood of realization of deferred tax assets using a “more likely than not” March 31, 2021 In response to the COVID- 19 March 27, 2020. December 27, 2020, 2020 2021, March 1, 2021. 2021 2022 not 2021.

Note 17 - Geographic Informatio

Note 17 - Geographic Information	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Segment Reporting Disclosure [Text Block]	Note 17. ​ The Company operates in one reportable segment. The Company’s Chief Executive Officer, who is considered to be the chief operating decision maker, manages the Company’s operations as a whole and reviews financial information presented on a consolidated basis, accompanied by information about product revenue, for purposes of evaluating financial performance and allocating resources. ​ The following tables set forth the Company’s revenue and asset information by geographic region. Revenue is classified based on the location of where the product is manufactured. Long-lived assets in the tables below comprise only property, plant, equipment and intangible assets (in thousands): ​ Three months ended March 31, ​ 2021 2020 Revenues: ​ ​ United States $ 3,316 $ 3,761 Taiwan 26,395 23,514 China 19,990 13,192 ​ $ 49,701 $ 40,467 ​ As of the period ended ​ March 31, December 31, ​ 2021 2020 Long-lived assets: ​ ​ United States $ 90,553 $ 90,999 Taiwan 67,986 71,080 China 107,053 108,575 ​ $ 265,592 $ 270,654 ​

Note 18 - Contingencies

Note 18 - Contingencies	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	Note 18. ​ Litigation ​ Overview From time to time, the Company may not Except for the lawsuits described below, the Company believes that there are no Class Action and Shareholder Derivative Litigation On August 7, 2018, Lei Jin, derivatively on behalf of Applied Optoelectronics, Inc. v. Chih-Hsiang ( Thompson ) Lin, Stefan J. Murry, William H. Yeh, Alex Ignatiev, Richard B. Black, Min-Chu Chen, Alan Moore, and Che-Wei Lin and Applied Optoelectronics, Inc. No. 4:18 02713 14 Mona Abouzied v. Applied Optoelectronics, Inc., Chih-Hsiang (Thompson) Lin, and Stefan J. Murry, et al. No. 4:17 02399, 2020. December 18, 2018, second Yiu Kwong Ng v. Chih-Hsiang ( Thompson ) Lin, Stefan J. Murry, William H. Yeh, Alex Ignatiev, Richard B. Black, Min-Chu Chen, Alan Moore, and Che-Wei Lin and Applied Optoelectronics, Inc. No. 4:18 4751 Jin September 28, 2018 25G January 11, 2019, two January 15, 2019, June 24, 2020, July 2, 2020, August 3, 2020. December 2, 2020. December 2, 2020, December 7, 2020, January 13, 2021. March 1, 2021. May 3, 2021. 21 May 3, 2021. not

Note 19 - Subsequent Events

Note 19 - Subsequent Events	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Subsequent Events [Text Block]	Note 19. ​ The Company repaid its revolving bank line of credit with Truist Bank in the amount of $18.7 million in April 2021. On April 5, 2021, September 28, 2017. April 2, 2021 October 15, 2022.

Significant Accounting Policies

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Business Overview [Policy Text Block]	Business Overview ​ Applied Optoelectronics, Inc. (“AOI” or the “Company”) is a Delaware corporation. The Company is a leading, vertically integrated provider of fiber-optic networking products, primarily for four ​ The Company has manufacturing and research and development facilities located in the U.S., Taiwan and China. In the U.S., at its corporate headquarters and manufacturing facilities in Sugar Land, Texas, the Company primarily manufactures lasers and laser components and performs research and development activities for laser component and optical module products. In addition, the Company also has a research and development facility in Duluth, Georgia. The Company operates in Taipei, Taiwan and Ningbo, China through its wholly-owned subsidiary Prime World International Holdings, Ltd. (“Prime World”, incorporated in the British Virgin Islands). Prime World operates a branch in Taipei, Taiwan, which primarily manufactures transceivers and performs research and development activities for the transceiver products. Prime World is also the parent of Global Technology, Inc. (“Global”, incorporated in the People’s Republic of China). Through Global, the Company primarily manufactures certain of its data center transceiver products, including subassemblies, as well as CATV systems and equipment, and performs research and development activities for the CATV products.
Basis of Accounting, Policy [Policy Text Block]	Interim Financial Statements ​ The unaudited condensed consolidated financial statements of the Company as of March 31, 2021 December 31, 2020 three March 31, 2021 March 31, 2020 10 10 01 X 10 December 31, 2020 three March 31, 2021 not
Use of Estimates, Policy [Policy Text Block]	Use of Estimates ​ The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported. Actual results could differ from those estimates in the consolidated financial statements and accompanying notes. Significant estimates and assumptions that impact these financial statements and the accompanying notes relate to, among other things, allowance for credit losses, inventory reserve, product warranty costs, share-based compensation expense, estimated useful lives of property and equipment, and taxes. ​

Note 3 - Revenue Recognition (T

Note 3 - Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Disaggregation of Revenue [Table Text Block]	Three months ended March 31, ​ % of % of ​ 2021 Revenue 2020 Revenue Data Center $ 25,939 52.2 % $ 33,264 82.2 % CATV 18,638 37.5 % 4,223 10.4 % Telecom 4,479 9.0 % 2,560 6.3 % FTTH 423 0.9 % - 0.0 % Other 222 0.4 % 420 1.0 % Total Revenue $ 49,701 100.0 % $ 40,467 100.0 %

Note 4 - Leases (Tables)

Note 4 - Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Lease, Cost [Table Text Block]	Three months ended March 31, ​ 2021 2020 Operating lease expense $ 303 $ 295 Financing lease expense 8 8 Short Term lease expense 9 21 Total lease expense $ 320 $ 324 March 31, ​ 2021 2020 Weighted Average Remaining Lease Term (Years) - operating leases 7.84 8.87 Weighted Average Remaining Lease Term (Years) - financing leases 2.58 3.57 Weighted Average Discount Rate - operating leases 3.23 % 3.17 % Weighted Average Discount Rate - financing leases 5.00 % 5.00 % Three months ended March 31, ​ 2021 2020 Cash paid for amounts included in the measurement of lease liabilities ​ ​ Operating cash flows from operating leases 330 318 Operating cash flows from financing lease 1 1 Financing cash flows from financing lease 4 4 Right-of-use assets obtained in exchange for new operating lease liabilities 0 261
Lessee, Operating and Finance Lease, Liability, Maturity [Table Text Block]	Operating Financing 2022 $ 1,335 $ 22 2023 1,328 22 2024 1,247 60 2025 1,249 — 2026 1,278 — 2027 and thereafter 3,892 — Total lease payments $ 10,329 $ 104 Less imputed interest (1,654 ) (9 ) Present value $ 8,675 $ 95

Note 5 - Cash, Cash Equivalen_2

Note 5 - Cash, Cash Equivalents and Restricted Cash (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Cash and Cash Equivalents [Table Text Block]	March 31, December 31, ​ 2021 2020 Cash and cash equivalents $ 45,482 $ 43,425 Restricted cash 3,856 6,689 Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 49,338 $ 50,114

Note 6 - Earnings (Loss) Per _2

Note 6 - Earnings (Loss) Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three months ended March 31, ​ 2021 2020 Numerator: ​ ​ Net loss $ (15,622 ) $ (16,797 ) Denominator: ​ ​ Weighted average shares used to compute net loss per share ​ ​ Basic 26,438 20,208 Diluted 26,438 20,208 Net loss per share ​ ​ Basic $ (0.59 ) $ (0.83 ) Diluted $ (0.59 ) $ (0.83 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Three months ended March 31, ​ 2021 2020 Employee stock options 13 26 Restricted stock units 20 22 Shares for convertible senior notes 4,587 4,587 Total antidilutive shares 4,620 4,635

Note 7 - Inventories (Tables)

Note 7 - Inventories (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Inventory, Current [Table Text Block]	​ March 31, 2021 December 31, 2020 Raw materials $ 28,304 $ 25,555 Work in process and sub-assemblies 49,194 52,544 Finished goods 28,838 32,298 Total inventories $ 106,336 $ 110,397

Note 8 - Property, Plant and _2

Note 8 - Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Property, Plant and Equipment [Table Text Block]	​ March 31, 2021 December 31, 2020 Land improvements $ 806 $ 806 Building and improvements 88,194 88,280 Machinery and equipment 255,530 253,738 Furniture and fixtures 5,520 5,540 Computer equipment and software 12,005 11,912 Transportation equipment 696 699 ​ 362,751 360,975 Less accumulated depreciation and amortization (148,029 ) (142,434 ) ​ 214,722 218,541 Construction in progress 32,480 33,342 Land 1,101 1,101 Total property, plant and equipment, net $ 248,303 $ 252,984

Note 9 - Intangible Assets, N_2

Note 9 - Intangible Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Finite-Lived Intangible Assets [Table Text Block]	March 31, 2021 ​ Gross Accumulated Intangible ​ Amount amortization assets, net Patents $ 8,251 $ (4,314 ) $ 3,937 Trademarks 22 (16 ) 6 Total intangible assets $ 8,273 $ (4,330 ) $ 3,943 December 31, 2020 ​ Gross Accumulated Intangible ​ Amount amortization assets, net Patents $ 8,158 $ (4,165 ) $ 3,993 Trademarks 21 (15 ) 6 Total intangible assets $ 8,179 $ (4,180 ) $ 3,999
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	2022 $ 588 2023 588 2024 588 2025 588 2026 588 thereafter 1,003 $ 3,943

Note 10 - Fair Value of Finan_2

Note 10 - Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	As of March 31, 2021 As of December 31, 2020 ​ (Level 1) (Level 2) (Level 3) Total (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents $ 45,482 $ — $ — $ 45,482 $ 43,425 $ — $ — $ 43,425 Restricted cash 3,856 — — 3,856 $ 6,689 — — 6,689 Total assets $ 49,338 $ — $ — $ 49,338 $ 50,114 $ — $ — $ 50,114 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ Bank acceptance payable $ — $ 6,344 $ — $ 6,344 $ — $ 15,860 $ — 15,860 Convertible senior notes — 70,526 — 70,526 — 70,225 — 70,225 Total liabilities $ — $ 76,870 $ — $ 76,870 $ — $ 86,085 $ — $ 86,085

Note 11 - Notes Payable and L_2

Note 11 - Notes Payable and Long-term Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Debt [Table Text Block]	March 31, 2021 December 31, 2020 Revolving line of credit with a U.S. bank up to $20,000 with interest at LIBOR plus 1.5% , maturing April 2, 2021 $ 18,700 $ 18,700 Paycheck Protection Program Term Note with interest at fixed rate 1.0%, maturing April 16, 2022 6,229 6,229 Revolving line of credit with a Taiwan bank up to $3,436 with 2.2% interest, maturing April 14, 2021 1,752 1,756 Notes payable to a finance company due in monthly installments with 3.5% interest, maturing January 21, 2022 1,410 1,941 Notes payable to a finance company due in monthly installments with 3.1% interest, maturing January 21, 2022 1,650 2,149 Revolving line of credit with a China bank up to $8,917 with interest ranging from 4.5%, maturing October 14, 2020 — 2,299 Revolving line of credit with a China bank up to $25,449 with interest from 3.01% to 4.57%, maturing May 24, 2024 15,785 11,603 Credit facility with a China bank up to $14,125 with interest of 3.5%, maturing January 5, 2024 11,506 — Credit facility with a China bank up to $7,167 with interest of 5.7%, maturing from June 20, 2022 7,457 7,510 Sub-total 64,489 52,187 Less debt issuance costs, net - (18 ) Grand total 64,489 52,169 Less current portion (50,803 ) (38,265 ) Non-current portion $ 13,686 $ 13,904 ​ ​ ​ Bank Acceptance Notes Payable ​ ​ Bank acceptance notes issued to vendors with a zero percent interest rate $ 6,344 $ 15,860
Schedule of Maturities of Long-term Debt [Table Text Block]	2022 $ 50,803 2023 13,686 Total outstanding $ 64,489

Note 12 - Convertible Senior _2

Note 12 - Convertible Senior Notes (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Convertible Debt [Table Text Block]	March 31, December 31, ​ 2021 2020 Principal $ 80,500 $ 80,500 Unamortized debt issuance costs (2,442 ) (2,646 ) Net carrying amount $ 78,058 $ 77,854
Interest Income and Interest Expense Disclosure [Table Text Block]	Three months ended March 31, ​ 2021 2020 Contractual interest expense $ 1,006 $ 1,006 Amortization of debt issuance costs 204 208 Total interest cost $ 1,210 $ 1,214 Effective interest rate 5.1 % 5.1 %

Note 13 - Accrued Liabilities (

Note 13 - Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Accrued Liabilities [Table Text Block]	March 31, 2021 December 31, 2020 Accrued payroll $ 6,963 $ 10,517 Accrued employee benefits 2,871 3,057 Accrued state and local taxes 722 251 Accrued interest 297 1,256 Advance payments 566 303 Accrued product warranty 502 703 Accrued commission expenses 1,157 974 Accrued professional fees 281 377 Accrued shipping and tariff expenses 48 526 Accrued other 622 547 Total accrued liabilities $ 14,028 $ 18,511

Note 14 - Other Income and Ex_2

Note 14 - Other Income and Expense (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Other Nonoperating Income (Expense) [Table Text Block]	Three months ended March 31, ​ 2021 2020 Foreign exchange transaction (loss) gain $ (208 ) $ 139 Government subsidy income 38 105 Other non-operating gain (loss) 1 12 Total other income (expense), net $ (169 ) $ 256

Note 15 - Share-based Compens_2

Note 15 - Share-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Share-based Payment Arrangement, Option, Activity [Table Text Block]	​ ​ Weighted ​ Weighted ​ ​ ​ Weighted Average ​ Average ​ ​ ​ Average Share Price Weighted Remaining Aggregate ​ Number of Exercise on Date of Average Contractual Intrinsic ​ shares Price Exercise Fair Value Life Value ​ (in thousands, except price data) Outstanding at January 1, 2021 276 $ 10.29 ​ $ 5.41 2.67 $ 54 Exercised (2 ) 6.00 — ​ 7 Forfeited (1 ) 6.00 ​ — Outstanding, March 31, 2021 273 $ 10.32 ​ $ 5.44 2.44 43 Exercisable, March 31, 2021 273 $ 10.32 ​ ​ 2.44 43 Vested and expected to vest 273 $ 10.33 ​ ​ 2.44 43
Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]	​ Weighted ​ ​ ​ ​ Average Share Weighted Aggregate ​ Number of Price on Date Average Fair Intrinsic ​ shares of Release Value Value ​ (in thousands, except price data) Outstanding at January 1, 2021 1,325 ​ $ 14.97 $ 11,279 Granted 231 ​ 12.3 2,843 Released (189 ) $ 10.23 19.89 1,931 Cancelled/Forfeited (28 ) ​ 13.56 232 Outstanding, March 31, 2021 1,340 ​ 13.84 11,202 Vested and expected to vest 1,340 ​ 13.84 11,202
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	Three months ended ​ March 31, ​ 2021 2020 Share-based compensation - by expense type ​ ​ Cost of goods sold $ 201 $ 246 Research and development 563 688 Sales and marketing 219 291 General and administrative 1,536 2,013 Total share-based compensation expense $ 2,519 $ 3,238

Note 17 - Geographic Informat_2

Note 17 - Geographic Information (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Revenue from External Customers by Geographic Areas [Table Text Block]	Three months ended March 31, ​ 2021 2020 Revenues: ​ ​ United States $ 3,316 $ 3,761 Taiwan 26,395 23,514 China 19,990 13,192 ​ $ 49,701 $ 40,467
Long-lived Assets by Geographic Areas [Table Text Block]	As of the period ended ​ March 31, December 31, ​ 2021 2020 Long-lived assets: ​ ​ United States $ 90,553 $ 90,999 Taiwan 67,986 71,080 China 107,053 108,575 ​ $ 265,592 $ 270,654

Note 3 - Revenue Recognition -

Note 3 - Revenue Recognition - Revenue by Major Product Category (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Total Revenue	$ 49,701	$ 40,467
Percent of Revenue	100.00%	100.00%
Data Center [Member]
Total Revenue	$ 25,939	$ 33,264
Percent of Revenue	52.20%	82.20%
CATV [Member]
Total Revenue	$ 18,638	$ 4,223
Percent of Revenue	37.50%	10.40%
Telecom [Member]
Total Revenue	$ 4,479	$ 2,560
Percent of Revenue	9.00%	6.30%
FTTH [Member]
Total Revenue	$ 423	$ 0
Percent of Revenue	0.90%	0.00%
Product and Service, Other [Member]
Total Revenue	$ 222	$ 420
Percent of Revenue	0.40%	1.00%

Note 4 - Leases - Components of

Note 4 - Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating lease expense	$ 303	$ 295
Financing lease expense	8	8
Short Term lease expense	9	21
Total lease expense	$ 320	$ 324
Weighted Average Remaining Lease Term (Years) - operating leases (Year)	7 years 10 months 2 days	8 years 10 months 13 days
Weighted Average Remaining Lease Term (Years) - financing leases (Year)	2 years 6 months 29 days	3 years 6 months 25 days
Weighted Average Discount Rate - operating leases	3.23%	3.17%
Weighted Average Discount Rate - financing leases	5.00%	5.00%
Operating cash flows from operating leases	$ 330	$ 318
Operating cash flows from financing lease	1	1
Financing cash flows from financing lease	4	4
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 0	$ 261

Note 4 - Leases - Maturities of

Note 4 - Leases - Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2021USD ($)
2022, operating leases	$ 1,335
2022, financing leases	22
2023, operating leases	1,328
2023, financing leases	22
2024, operating leases	1,247
2024, financing leases	60
2025, operating leases	1,249
2025, financing leases	0
2026, operating leases	1,278
2026, financing leases	0
2027 and thereafter, operating leases	3,892
2027 and thereafter, financing leases	0
Total operating lease payments	10,329
Total financing lease payments	104
Less imputed interest, operating leases	(1,654)
Less imputed interest, financing leases	(9)
Present value, operating leases	8,675
Present value, financing leases	$ 95

Note 5 - Cash, Cash Equivalen_3

Note 5 - Cash, Cash Equivalents and Restricted Cash (Details Textual) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Restricted Cash and Cash Equivalents, Current, Total	$ 3,856	$ 6,689
CHINA
Certificates of Deposit, at Carrying Value	400	500
Bankers Acceptance [Member]
Restricted Cash and Cash Equivalents, Current, Total	$ 2,200	$ 4,900

Note 5 - Cash, Cash Equivalen_4

Note 5 - Cash, Cash Equivalents and Restricted Cash - Summary of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and cash equivalents	$ 45,482	$ 43,425
Restricted cash	3,856	6,689
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 49,338	$ 50,114

Note 6 - Earnings (Loss) Per _3

Note 6 - Earnings (Loss) Per Share - Computation of Basic and Diluted Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net loss	$ (15,622)	$ (16,797)
Basic (in shares)	26,438,071	20,208,383
Diluted (in shares)	26,438,071	20,208,383
Basic (in dollars per share)	$ (0.59)	$ (0.83)
Diluted (in dollars per share)	$ (0.59)	$ (0.83)

Note 6 - Earnings (Loss) Per _4

Note 6 - Earnings (Loss) Per Share - Potentially Dilutive Securities Excluded from Diluted Net Income (Loss) per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Total antidilutive shares (in shares)	4,620	4,635
Share-based Payment Arrangement, Option [Member]
Total antidilutive shares (in shares)	13	26
Restricted Stock Units (RSUs) [Member]
Total antidilutive shares (in shares)	20	22
Convertible Debt Securities [Member]
Total antidilutive shares (in shares)	4,587	4,587

Note 7 - Inventories (Details T

Note 7 - Inventories (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Inventory, LIFO Reserve, Period Charge	$ 937	$ 1,648
Inventory Write-down	$ 6,000	$ 2,500

Note 7 - Inventories - Inventor

Note 7 - Inventories - Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Raw materials	$ 28,304	$ 25,555
Work in process and sub-assemblies	49,194	52,544
Finished goods	28,838	32,298
Total inventories	$ 106,336	$ 110,397

Note 8 - Property, Plant and _3

Note 8 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Depreciation, Total	$ 6.3	$ 5.9
Interest Paid, Capitalized, Investing Activities	$ 0.1	$ 0.1

Note 8 - Property, Plant and _4

Note 8 - Property, Plant and Equipment - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, plant and equipment, gross	$ 362,751	$ 360,975
Less accumulated depreciation and amortization	(148,029)	(142,434)
Property, plant and equipment, net before construction in progress and land	214,722	218,541
Property, plant and equipment, net	248,303	252,984
Land Improvements [Member]
Property, plant and equipment, gross	806	806
Building and Building Improvements [Member]
Property, plant and equipment, gross	88,194	88,280
Machinery and Equipment [Member]
Property, plant and equipment, gross	255,530	253,738
Furniture and Fixtures [Member]
Property, plant and equipment, gross	5,520	5,540
Computer Equipment and Software [Member]
Property, plant and equipment, gross	12,005	11,912
Vehicles [Member]
Property, plant and equipment, gross	696	699
Construction in Progress [Member]
Property, plant and equipment, net	32,480	33,342
Land [Member]
Property, plant and equipment, net	$ 1,101	$ 1,101

Note 9 - Intangible Assets, N_3

Note 9 - Intangible Assets, Net (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Amortization of Intangible Assets, Total	$ 0.1	$ 0.1
Finite-Lived Intangible Assets, Remaining Amortization Period (Year)	7 years

Note 9 - Intangible Assets, N_4

Note 9 - Intangible Assets, Net - Finite Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Intangible assets, gross amount	$ 8,273	$ 8,179
Intangible assets, accumulated amortization	(4,330)	(4,180)
Intangible assets, net	3,943	3,999
Patents [Member]
Intangible assets, gross amount	8,251	8,158
Intangible assets, accumulated amortization	(4,314)	(4,165)
Intangible assets, net	3,937	3,993
Trademarks [Member]
Intangible assets, gross amount	22	21
Intangible assets, accumulated amortization	(16)	(15)
Intangible assets, net	$ 6	$ 6

Note 9 - Intangible Assets, N_5

Note 9 - Intangible Assets, Net - Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
2022	$ 588
2023	588
2024	588
2025	588
2026	588
thereafter	1,003
Finite-Lived Intangible Assets, Net, Ending Balance	$ 3,943	$ 3,999

Note 10 - Fair Value of Finan_3

Note 10 - Fair Value of Financial Instruments - Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and cash equivalents	$ 45,482	$ 43,425
Restricted cash	3,856	6,689
Total assets	49,338	50,114
Bank acceptance payable	6,344	15,860
Convertible senior notes	70,526	70,225
Total liabilities	76,870	86,085
Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	45,482	43,425
Restricted cash	3,856	6,689
Total assets	49,338	50,114
Bank acceptance payable	0	0
Convertible senior notes	0	0
Total liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0	0
Restricted cash	0	0
Total assets	0	0
Bank acceptance payable	6,344	15,860
Convertible senior notes	70,526	70,225
Total liabilities	76,870	86,085
Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0	0
Restricted cash	0	0
Total assets	0	0
Bank acceptance payable	0	0
Convertible senior notes	0	0
Total liabilities	$ 0	$ 0

Note 11 - Notes Payable and L_3

Note 11 - Notes Payable and Long-term Debt (Details Textual)

Jan. 21, 2022USD ($)

Jan. 21, 2022TWD ($)

Oct. 07, 2020USD ($)

Sep. 15, 2020USD ($)

Sep. 15, 2020TWD ($)

Apr. 17, 2020USD ($)

Sep. 30, 2019USD ($)

Jul. 23, 2019USD ($)

Jun. 21, 2019USD ($)

May 24, 2019USD ($)

Apr. 19, 2019USD ($)

Mar. 05, 2019USD ($)

Jan. 21, 2019USD ($)

Jan. 21, 2019TWD ($)

Nov. 29, 2018USD ($)

Nov. 29, 2018TWD ($)

Mar. 30, 2018USD ($)

Sep. 28, 2017USD ($)

Mar. 31, 2021USD ($)

Mar. 31, 2020USD ($)

Dec. 31, 2020USD ($)

Oct. 19, 2020USD ($)

Oct. 19, 2020CNY (¥)

Oct. 07, 2020TWD ($)

Jul. 23, 2019TWD ($)

Jun. 21, 2019CNY (¥)

May 24, 2019CNY (¥)

Apr. 19, 2019CNY (¥)

Jan. 21, 2019TWD ($)

Nov. 29, 2018TWD ($)

Long-term Debt, Gross

$ 64,489,000

$ 52,187,000

Payments to Acquire Property, Plant, and Equipment, Total

2,212,000

$ 2,787,000

Finance Lease, Principal Payments

4,000

$ 4,000

Debt Instrument, Unused Borrowing Capacity, Amount

$ 21,800,000

$ 28,700,000

LIBOR Rate

0.11%

0.14%

Cash Collateral for Borrowed Securities

$ 2,600,000

$ 5,400,000

Chailease Finance Co, Ltd. [Member] | Promissory Note [Member]

Long-term Debt, Gross

1,410,000

1,941,000

Chailease Finance Co, Ltd. [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member] | Forecast [Member]

Payments to Acquire Property, Plant, and Equipment, Total

$ 800,000

$ 22,311,381

Chailease Finance Co, Ltd. [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member] | Promissory Note [Member]

Debt Instrument, Face Amount

$ 6,800,000

$ 210,601,605

Long-term Debt, Gross

1,400,000

Chailease Finance Co, Ltd. [Member] | Finance Lease Agreement 2 [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Sale Leaseback Transaction, Net Proceeds, Investing Activities, Total

$ 8,700,000

$ 267,340,468

Sale Leaseback Transaction, Term (Year)

3 years

3 years

Sale Leaseback Transaction, Initial Payment

$ 2,200,000

$ 67,340,468

Sale Leaseback Transaction, Imputed Interest Rate

3.50%

3.50%

Chailease Finance Co, Ltd. [Member] | Second Sales Contract [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Sale Leaseback Transaction, Net Proceeds, Investing Activities, Total

$ 8,700,000

$ 267,333,186

Sale Leaseback Transaction, Term (Year)

3 years

3 years

Sale Leaseback Transaction, Initial Payment

$ 2,200,000

$ 67,333,186

Sale Leaseback Transaction, Imputed Interest Rate

3.10%

3.10%

Finance Lease, Principal Payments

$ 5,500,000

$ 159,027,448

Chailease Finance Co, Ltd. [Member] | Second Sales Contract [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member] | Promissory Note [Member]

Debt Instrument, Face Amount

$ 6,800,000

$ 209,555,736

Long-term Debt, Gross

1,700,000

Minimum [Member] | Chailease Finance Co, Ltd. [Member] | Finance Lease Agreement 2 [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Sale Leaseback Transaction, Monthly Rental Payments

$ 200,000

$ 5,571,229

Minimum [Member] | Chailease Finance Co, Ltd. [Member] | Second Sales Contract [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Sale Leaseback Transaction, Monthly Rental Payments

200,000

$ 5,570,167

Maximum [Member] | Chailease Finance Co, Ltd. [Member] | Finance Lease Agreement 2 [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Sale Leaseback Transaction, Monthly Rental Payments

$ 200,000

$ 6,139,188

Maximum [Member] | Chailease Finance Co, Ltd. [Member] | Second Sales Contract [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Sale Leaseback Transaction, Monthly Rental Payments

$ 200,000

$ 6,082,131

Paycheck Protection Program, CARES Act [Member]

Proceeds from Issuance of Long-term Debt, Total

$ 6,230,000

Long-term Debt, Gross

6,229,000

6,229,000

Truist Bank [Member] | CapEx Loan [Member]

Debt Instrument, Term (Year)

5 years

Debt Instrument, Face Amount

$ 26,000,000

Truist Bank [Member] | Term Loan [Member]

Debt Instrument, Term (Year)

70 months

Debt Instrument, Face Amount

$ 21,500,000

Truist Bank [Member] | CapEx Loan and Term Loan [Member]

Repayments of Long-term Debt, Total

$ 37,800,000

Truist Bank [Member] | London Interbank Offered Rate (LIBOR) [Member] | CapEx Loan [Member] | Minimum [Member]

Debt Instrument, Basis Spread on Variable Rate

1.30%

Truist Bank [Member] | London Interbank Offered Rate (LIBOR) [Member] | CapEx Loan [Member] | Maximum [Member]

Debt Instrument, Basis Spread on Variable Rate

2.00%

Truist Bank [Member] | London Interbank Offered Rate (LIBOR) [Member] | Term Loan [Member] | Minimum [Member]

Debt Instrument, Basis Spread on Variable Rate

1.15%

Truist Bank [Member] | London Interbank Offered Rate (LIBOR) [Member] | Term Loan [Member] | Maximum [Member]

Debt Instrument, Basis Spread on Variable Rate

2.00%

Revolving Credit Facility [Member] | The NT$100M Credit Line [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Line of Credit Facility, Maximum Borrowing Capacity

$ 100,000,000

Revolving Credit Facility [Member] | Truist Bank [Member]

Debt Instrument, Term (Year)

3 years

3 years

Line of Credit Facility, Maximum Borrowing Capacity

$ 20,000,000

$ 25,000,000

$ 60,000,000

$ 50,000,000

Debt Instrument, Unused Borrowing Capacity, Fee, Percentage

0.30%

0.20%

Line of Credit Facility, Percentage of Maximum Borrowing Capacity, Threshold for Financial Covenants

75.00%

60.00%

Fixed Charge Cover Ratio, Minimum Threshold

1.5

Long-term Line of Credit, Total

18,700,000

Revolving Credit Facility [Member] | Truist Bank [Member] | London Interbank Offered Rate (LIBOR) [Member]

Debt Instrument, Basis Spread on Variable Rate

1.50%

Revolving Credit Facility [Member] | Truist Bank [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]

Debt Instrument, Basis Spread on Variable Rate

1.40%

Revolving Credit Facility [Member] | Truist Bank [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]

Debt Instrument, Basis Spread on Variable Rate

2.00%

Revolving Credit Facility [Member] | Taishin International Bank [Member] | The NT$100M Credit Line [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Debt Instrument, Term (Year)

1 year

Line of Credit Facility, Maximum Borrowing Capacity

$ 3,300,000

$ 100,000,000

Revolving Credit Facility [Member] | Taishin International Bank [Member] | The US $1M Credit Line [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Line of Credit Facility, Maximum Borrowing Capacity

$ 1,000,000

Revolving Credit Facility [Member] | Taishin International Bank [Member] | Credit Facility [Member]

Long-term Debt, Gross

$ 1,752,000

1,756,000

Revolving Credit Facility [Member] | Taishin International Bank [Member] | Credit Facility [Member] | Minimum [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Debt Instrument, Term of Draw (Day)

90 days

Debt Instrument, Interest Rate, Stated Percentage

2.25%

Revolving Credit Facility [Member] | Taishin International Bank [Member] | Credit Facility [Member] | Maximum [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Debt Instrument, Term of Draw (Day)

120 days

Debt Instrument, Interest Rate, Stated Percentage

2.20%

Revolving Credit Facility [Member] | Taishin International Bank in Taiwan [Member] | The NT$100M Credit Line [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Line of Credit Facility, Maximum Borrowing Capacity

$ 3,440,000

Long-term Line of Credit, Total

$ 1,800,000

Debt Instrument, Interest Rate, Stated Percentage

2.15%

2.15%

Revolving Credit Facility [Member] | Taishin International Bank in Taiwan [Member] | The NT$100M Credit Line [Member] | Minimum [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Debt Instrument, Term of Draw (Day)

90 days

Revolving Credit Facility [Member] | Taishin International Bank in Taiwan [Member] | The NT$100M Credit Line [Member] | Maximum [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Debt Instrument, Term of Draw (Day)

120 days

Revolving Credit Facility [Member] | Taishin International Bank in Taiwan [Member] | The US $1M Credit Line [Member] | Prime World International Holdings, Ltd. (“Prime World”) [Member]

Line of Credit Facility, Maximum Borrowing Capacity

$ 1,000,000

Revolving Credit Facility [Member] | China Construction Bank Co., Ltd. [Member] | China Merchants Credit Line [Member] | Global Technology, Inc. [Member]

Debt Instrument, Term (Year)

12 months

Line of Credit Facility, Maximum Borrowing Capacity

$ 8,900,000

¥ 60,000,000

¥ 60,000,000

Long-term Line of Credit, Total

0

Bank Acceptances Executed

3,000,000

Revolving Credit Facility [Member] | China Merchants Bank Co, Ltd [Member]

Long-term Debt, Gross

0

2,299,000

Revolving Credit Facility [Member] | China Merchants Bank Co, Ltd [Member] | China Merchants Credit Line [Member] | Global Technology, Inc. [Member]

Line of Credit Facility, Maximum Borrowing Capacity

$ 8,900,000

Revolving Credit Facility [Member] | SPD Bank [Member]

Long-term Debt, Gross

15,785,000

11,603,000

Revolving Credit Facility [Member] | SPD Bank [Member] | The SPD Credit Line [Member] | Global Technology, Inc. [Member]

Debt Instrument, Term (Year)

5 years

Line of Credit Facility, Maximum Borrowing Capacity

$ 25,400,000

¥ 180,000,000

Long-term Line of Credit, Total

15,800,000

Bank Acceptances Executed

3,400,000

Revolving Credit Facility [Member] | China Zheshang Bank Co., Ltd [Member] | The ¥100M Credit Facility [Member]

Long-term Debt, Gross

11,506,000

0

Revolving Credit Facility [Member] | China Zheshang Bank Co., Ltd [Member] | The ¥100M Credit Facility [Member] | Global Technology, Inc. [Member]

Debt Instrument, Term (Year)

18 months

Line of Credit Facility, Maximum Borrowing Capacity

$ 14,100,000

¥ 100,000,000

Long-term Line of Credit, Total

11,500,000

Bank Acceptances Executed

0

Revolving Credit Facility [Member] | China Zheshang Bank Co., Ltd [Member] | The ¥50M Credit Facility [Member]

Long-term Debt, Gross

$ 7,457,000

7,510,000

Revolving Credit Facility [Member] | China Zheshang Bank Co., Ltd [Member] | The ¥50M Credit Facility [Member] | Global Technology, Inc. [Member]

Debt Instrument, Term (Year)

3 years

Line of Credit Facility, Maximum Borrowing Capacity

$ 7,100,000

¥ 50,000,000

Long-term Line of Credit, Total

$ 7,500,000

Note 11 - Notes Payable and L_4

Note 11 - Notes Payable and Long-term Debt - Schedule of Notes Payable and Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Long-term debt	$ 64,489	$ 52,187
Less debt issuance costs, net	0	18
Grand total	64,489	52,169
Less current portion	50,803	38,265
Non-current portion	13,686	13,904
Bank acceptance notes issued to vendors with a zero percent interest rate	6,344	15,860
Chailease Finance Co, Ltd. [Member] | Promissory Note [Member]
Long-term debt	1,410	1,941
Chailease Finance Co, Ltd. [Member] | Promissory Note 2 [Member]
Long-term debt	1,650	2,149
Paycheck Protection Program, CARES Act [Member]
Long-term debt	6,229	6,229
Revolving Credit Facility [Member] | Truist Bank [Member] | Third Amendment to Loan Agreement with BB and T [Member]
Long-term debt	18,700	18,700
Revolving Credit Facility [Member] | Taishin International Bank [Member] | Credit Facility [Member]
Long-term debt	1,752	1,756
Revolving Credit Facility [Member] | China Merchants Bank Co, Ltd [Member]
Long-term debt	0	2,299
Revolving Credit Facility [Member] | SPD Bank [Member]
Long-term debt	15,785	11,603
Revolving Credit Facility [Member] | China Zheshang Bank Co., Ltd [Member] | The ¥100M Credit Facility [Member]
Long-term debt	11,506	0
Revolving Credit Facility [Member] | China Zheshang Bank Co., Ltd [Member] | The ¥50M Credit Facility [Member]
Long-term debt	$ 7,457	$ 7,510

Note 11 - Notes Payable and L_5

Note 11 - Notes Payable and Long-term Debt - Schedule of Notes Payable and Long-term Debt (Details) (Parentheticals) - Truist Bank [Member] - Revolving Credit Facility [Member] - USD ($)	Sep. 30, 2019	Mar. 05, 2019	Mar. 30, 2018	Sep. 28, 2017
Long-term debt, maximum	$ 20,000,000	$ 25,000,000	$ 60,000,000	$ 50,000,000
Third Amendment to Loan Agreement with BB and T [Member]
Long-term debt, maximum				$ 20,000,000

Note 11 - Notes Payable and L_6

Note 11 - Notes Payable and Long-term Debt - Maturities of Notes Payable and Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
2022	$ 50,803
2023	13,686
Total outstanding	$ 64,489	$ 52,169

Note 12 - Convertible Senior _3

Note 12 - Convertible Senior Notes (Details Textual) - USD ($)	Mar. 05, 2019	Mar. 31, 2021	Dec. 31, 2020
Truist Bank [Member] | CapEx Loan and Term Loan [Member]
Repayments of Long-term Debt, Total	$ 37,800,000
The 5% Convertible Senior Notes Due 2024 [Member]
Debt Instrument, Face Amount	$ 80,500,000	$ 80,500,000	$ 80,500,000
Debt Instrument, Interest Rate, Stated Percentage	5.00%
Proceeds from Convertible Debt	$ 76,400,000
Debt Conversion, Converted Instrument, Shares Issued (in shares)	56.9801
Debt Conversion, Converted Instrument, Amount	$ 1,000
Debt Instrument, Convertible, Conversion Price (in dollars per share)	$ 17.55
Debt Instrument, Convertible, Conversion Price Premium, Percentage	30.00%
Share Price (in dollars per share)	$ 13.50
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	130.00%
Debt Instrument, Convertible, Threshold Trading Days	20
Debt Instrument, Convertible, Threshold Consecutive Trading Days	30
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	100.00%
Debt Issuance Costs, Gross	$ 4,100,000

Note 12 - Convertible Senior _4

Note 12 - Convertible Senior Notes - Schedule of Carrying Value of Convertible Senior Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 05, 2019
Net carrying amount	$ 78,058	$ 77,854
The 5% Convertible Senior Notes Due 2024 [Member]
Principal	80,500	80,500	$ 80,500
Unamortized debt issuance costs	(2,442)	(2,646)
Net carrying amount	$ 78,058	$ 77,854

Note 12 - Convertible Senior _5

Note 12 - Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Amortization of debt issuance costs	$ 221	$ 220
The 5% Convertible Senior Notes Due 2024 [Member]
Contractual interest expense	1,006	1,006
Amortization of debt issuance costs	204	208
Total interest cost	$ 1,210	$ 1,214
Effective interest rate	5.10%	5.10%

Note 13 - Accrued Liabilities -

Note 13 - Accrued Liabilities - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accrued payroll	$ 6,963	$ 10,517
Accrued employee benefits	2,871	3,057
Accrued state and local taxes	722	251
Accrued interest	297	1,256
Advance payments	566	303
Accrued product warranty	502	703
Accrued commission expenses	1,157	974
Accrued professional fees	281	377
Accrued shipping and tariff expenses	48	526
Accrued other	622	547
Total accrued liabilities	$ 14,028	$ 18,511

Note 14 - Other Income and Ex_3

Note 14 - Other Income and Expense - Other Income and Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Foreign exchange transaction (loss) gain	$ (208)	$ 139
Government subsidy income	38	105
Other non-operating gain (loss)	1	12
Total other income (expense), net	$ (169)	$ 256

Note 15 - Share-based Compens_3

Note 15 - Share-based Compensation (Details Textual) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount	$ 0
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	10 years
Share-based Payment Arrangement, Option [Member] | Exercisable on the First Anniversary Date Following the Date of Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
Share-based Payment Arrangement, Option [Member] | Exercisable on Semi-annual Basis [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	12.50%
Restricted Stock Awards and Restricted Stock Units [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 16,800
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	2 years 5 months 19 days

Note 15 - Share-based Compens_4

Note 15 - Share-based Compensation - Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Outstanding, number of shares (in shares)	276
Outstanding, weighted average exercise price (in dollars per share)	$ 10.29
Outstanding, weighted average fair value (in dollars per share)	$ 5.44	$ 5.41
Outstanding, weighted average remaining contractual life (Year)	2 years 5 months 8 days	2 years 8 months 1 day
Outstanding, aggregate intrinsic value	$ 43	$ 54
Exercised, number of shares (in shares)	(2)
Exercised, weighted average exercise price (in dollars per share)	$ 6
Exercised, weighted average share price on date of exercise (in dollars per share)	$ 0
Exercised, aggregate intrinsic value	$ 7
Forfeited (in shares)	(1)
Forfeited, weighted average exercise price (in dollars per share)	$ 6
Forfeited, weighted average fair value (in dollars per share)
Forfeited, aggregate intrinsic value	$ 0
Outstanding, number of shares (in shares)	273	276
Outstanding, weighted average exercise price (in dollars per share)	$ 10.32	$ 10.29
Exercisable, number of shares (in shares)	273
Exercisable, weighted average exercise price (in dollars per share)	$ 10.32
Exercisable, weighted average remaining contractual life (Year)	2 years 5 months 8 days
Exercisable, aggregate intrinsic value	$ 43
Vested and expected to vest, number of shares (in shares)	273
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 10.33
Vested and expected to vest, weighted average remaining contractual life (Year)	2 years 5 months 8 days
Vested and expected to vest, aggregate intrinsic value	$ 43

Note 15 - Share-based Compens_5

Note 15 - Share-based Compensation - Restricted Stock Unit/Awards Activity (Details) - Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Outstanding, number of shares (in shares)	1,325
Outstanding, weighted average fair value (in dollars per share)	$ 13.84	$ 14.97
Outstanding, aggregate intrinsic value	$ 11,202	$ 11,279
Granted, number of shares (in shares)	231
Granted, weighted average fair value (in dollars per share)	$ 12.3
Granted, aggregate intrinsic value	$ 2,843
Released, number of shares (in shares)	(189)
Released, weighted average share price on date of release (in dollars per share)	$ 10.23
Released, weighted average fair value (in dollars per share)	$ 19.89
Released, aggregate intrinsic value	$ 1,931
Cancelled/Forfeited, number of shares (in shares)	(28)
Cancelled/Forfeited, weighted average fair value (in dollars per share)	$ 13.56
Cancelled/Forfeited, aggregate intrinsic value	$ 232
Outstanding, number of shares (in shares)	1,340
Vested and expected to vest, number of shares (in shares)	1,340
Vested and expected to vest, weighted average fair value (in dollars per share)	$ 13.84
Vested and expected to vest, aggregate intrinsic value	$ 11,202

Note 15 - Share-based Compens_6

Note 15 - Share-based Compensation - Share-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Total share-based compensation expense	$ 2,519	$ 3,238
Cost of Sales [Member]
Total share-based compensation expense	201	246
Research and Development Expense [Member]
Total share-based compensation expense	563	688
Selling and Marketing Expense [Member]
Total share-based compensation expense	219	291
General and Administrative Expense [Member]
Total share-based compensation expense	$ 1,536	$ 2,013

Note 16 - Income Taxes (Details

Note 16 - Income Taxes (Details Textual)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Effective Income Tax Rate Reconciliation, Percent, Total	0.00%	10.90%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%

Note 17 - Geographic Informat_3

Note 17 - Geographic Information (Details Textual)	3 Months Ended
	Mar. 31, 2021
Number of Reportable Segments	1

Note 17- Geographic Information

Note 17- Geographic Information - Revenue Information by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue, net	$ 49,701	$ 40,467
UNITED STATES
Revenue, net	3,316	3,761
TAIWAN, PROVINCE OF CHINA
Revenue, net	26,395	23,514
CHINA
Revenue, net	$ 19,990	$ 13,192

Note 17 - Geographic Informat_4

Note 17 - Geographic Information - Asset Information by Geographic Region (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Long-lived assets	$ 265,592	$ 270,654
UNITED STATES
Long-lived assets	90,553	90,999
TAIWAN, PROVINCE OF CHINA
Long-lived assets	67,986	71,080
CHINA
Long-lived assets	$ 107,053	$ 108,575

Note 19 - Subsequent Events (De

Note 19 - Subsequent Events (Details Textual) - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2021	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2019	Mar. 05, 2019	Mar. 30, 2018	Sep. 28, 2017
Repayments of Lines of Credit		$ 26,320,000	$ 20,000,000
Revolving Credit Facility [Member] | Truist Bank [Member]
Line of Credit Facility, Maximum Borrowing Capacity				$ 20,000,000	$ 25,000,000	$ 60,000,000	$ 50,000,000
Revolving Credit Facility [Member] | Truist Bank [Member] | Third Amendment to Loan Agreement with BB and T [Member]
Line of Credit Facility, Maximum Borrowing Capacity							$ 20,000,000
Revolving Credit Facility [Member] | Truist Bank [Member] | Third Amendment to Loan Agreement with BB and T [Member] | Subsequent Event [Member]
Repayments of Lines of Credit	$ 18,700,000