Segment and Revenue Information - Schedule of Revenue by Major Product Category (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenue	$ 26,820	$ 32,650	$ 51,773	$ 74,886
Inertial Navigation
Disaggregation of Revenue [Line Items]
Total revenue			44,229
Inertial Navigation | Aerospace And Defense
Disaggregation of Revenue [Line Items]
Total revenue	24,250	7,615		15,760
Defense Optoelectronics
Disaggregation of Revenue [Line Items]
Total revenue			2,649
Defense Optoelectronics | Aerospace And Defense
Disaggregation of Revenue [Line Items]
Total revenue	953	1,391		3,146
CATV Optical Transmitters and Components
Disaggregation of Revenue [Line Items]
Total revenue			1,947
CATV Optical Transmitters and Components | Broadband
Disaggregation of Revenue [Line Items]
Total revenue	394	20,984		49,443
Data Center Chips
Disaggregation of Revenue [Line Items]
Total revenue			1,197
Data Center Chips | Broadband
Disaggregation of Revenue [Line Items]
Total revenue	790	1,113		2,181
Optical Sensing
Disaggregation of Revenue [Line Items]
Total revenue			$ 1,751
Optical Sensing | Broadband
Disaggregation of Revenue [Line Items]
Total revenue	$ 433	$ 1,547		$ 4,356