Intangible Assets and Goodwill - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 17,894	$ 69	$ 69
In Process Research and Development
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	6,700
Trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	2,200
S & N and Emcore Chicago Acquisitions
Finite-Lived Intangible Assets [Line Items]
Goodwill	17,800
Expected tax deductible amount of goodwill	$ 0
Patents
Finite-Lived Intangible Assets [Line Items]
Intangible assets useful life (in years)	7 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets useful life (in years)	8 years
Maximum | Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets useful life (in years)	8 years
Minimum | Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets useful life (in years)	2 years