| Cover | Jan. 06, 2024 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 06, 2024 |
| Current Fiscal Year End Date | --09-30 |
| Entity File Number | 001-36632 |
| Entity Registrant Name | EMCORE CORPORATION |
| Entity Central Index Key | 0000808326 |
| Entity Tax Identification Number | 22-2746503 |
| Entity Incorporation, State or Country Code | NJ |
| Entity Address, Address Line One | 2015 W. Chestnut Street |
| Entity Address, City or Town | Alhambra |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 91803 |
| City Area Code | 626 |
| Local Phone Number | 293-3400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, no par value |
| Trading Symbol | EMKR |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
