Segment Information (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Product Information [Line Items]
Total revenue	$ 5,044	$ 19,630
Core [Member]
Product Information [Line Items]
Total revenue	26	1,652
Optical [Member]
Product Information [Line Items]
Total revenue	4,615	4,568
Wafer [Member]
Product Information [Line Items]
Total revenue	9	13,121
Research & development [Member]
Product Information [Line Items]
Total revenue	$ 394	$ 289