Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	$ 4,969	$ 59,180
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation, amortization and accretion expense	1,081	1,803
Stock-based compensation expense	920	3,760
Deferred income taxes	0	24,080
Provision adjustments related to doubtful accounts	4	463
Provision adjustments related to product warranty	234	515
Change in fair value of financial instruments	0	(122)
Gain from change in estimate on ARO obligation	0	(845)
Reclassification of foreign currency translation adjustment	0	(744)
Recognition of previously deferred gain on sale of assets from discontinued operations	(3,804)	0
Gain on reduction of product warranty of discontinued operations	(423)	0
Gain on settlement of solar power assets and obligations	(689)	0
Gain on settlement of Newark lease	(310)	0
Net loss on disposal of equipment	0	237
Settlement of customer related warranty claim	0	(280)
Total non-cash adjustments	(2,987)	(60,149)
Changes in operating assets and liabilities:
Accounts receivable	(2,017)	3,859
Inventory	228	(1,541)
Other assets	1,323	(913)
Accounts payable	1,172	(3,151)
Accrued expenses and other current liabilities	(2,412)	(3,012)
Total change in operating assets and liabilities	(1,706)	(4,758)
Net cash provided by (used in) operating activities	276	(5,727)
Cash flows from investing activities:
Purchase of equipment	(2,685)	(1,150)
(Increase) decrease in restricted cash	(155)	1,314
Proceeds from disposal of property, plant and equipment	0	50
Net cash (used in) provided by investing activities	(2,840)	151,714
Cash flows from financing activities:
Payments on credit facilities	0	(26,518)
Proceeds from stock plans	597	834
Net cash provided by (used in) financing activities	597	(25,684)
Effect of exchange rate changes on foreign currency	113	(25)
Net (decrease) increase in cash and cash equivalents	(1,854)	120,278
Cash and cash equivalents at beginning of period	111,885	20,687
Cash and cash equivalents at end of period	110,031	140,965
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	44	139
Cash paid during the period for income taxes	108	25
NON-CASH INVESTING AND FINANCING ACTIVITIES
Sale of Digital Products assets to NeoPhotonics for note receivable	0	15,482
Changes in accounts payable related to purchases of equipment	(191)	0
Issuance of common stock to Board of Directors	263	301
Photovoltaics Business [Member]
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Gain on sale of business	0	(87,022)
Cash flows from investing activities:
Proceeds from sale of business	0	150,000
Digital Products Business [Member]
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Gain on sale of business	0	(1,994)
Cash flows from investing activities:
Proceeds from sale of business	$ 0	$ 1,500