Segment and Revenue Information - Schedule of Revenue by Major Product Category (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenue	$ 26,698	$ 23,675	$ 78,471	$ 98,561
Inertial Navigation | Aerospace And Defense
Disaggregation of Revenue [Line Items]
Total revenue	26,718	9,891	70,947	25,651
Defense Optoelectronics | Aerospace And Defense
Disaggregation of Revenue [Line Items]
Total revenue	283	3,525	2,932	6,671
CATV Optical Transmitters and Components | Broadband
Disaggregation of Revenue [Line Items]
Total revenue	323	7,006	2,270	56,449
Data Center Chips | Broadband
Disaggregation of Revenue [Line Items]
Total revenue	(312)	1,353	885	3,534
Optical Sensing | Broadband
Disaggregation of Revenue [Line Items]
Total revenue	$ (314)	$ 1,900	$ 1,437	$ 6,256