8. STOCK- BASED COMPENSATION (Tables)

6 Months Ended

Sep. 30, 2017

STOCK- BASED COMPENSATION

Summary of stock option activities

			Weighted
		Number of Shares	Average	Weighted
	Shares	Underlying	Remaining	Average
	Available for	Options	Contractual	Exercise		Intrinsic
	Grant	Outstanding	Life (Years)	Price		Value
Balance at March 31, 2017	5,464,185	7,622,830		$	5.09
Granted	(658,983)	658,983		$	7.28
Exercised	—	(394,490)		$	4.48	$	1,291,881
Forfeited	9,800	(92,700)		$	5.02
Balance at September 30, 2017	4,815,002	7,794,623	5.74	$	5.30
Options vested and exercisable		4,851,100	4.02	$	5.18	$	10,344,300
Options vested and expected to vest		7,719,879	5.70	$	5.30	$	15,453,096

Schedule of options outstanding by exercise price

				Number of	Options Outstanding			Options Exercisable
				Shares	Weighted		Weighted Average		Weighted
				Underlying	Average		Remaining	Number	Average
				Options	Exercise		Contractual	Vested and	Exercise
Exercise Price				Outstanding	Price		Life (Years)	Exercisable	Price
$	2.43	-	3.43	962,345	$	3.30	3.55	735,612	$	3.26
$	3.60	-	4.00	794,446	$	3.92	2.69	699,352	$	3.96
$	4.17	-	4.90	902,210	$	4.53	4.81	847,985	$	4.54
$	4.92	-	4.99	1,194,039	$	4.98	8.11	195,237	$	4.96
$	5.13	-	5.34	813,812	$	5.24	7.57	223,804	$	5.25
$	5.59	-	6.16	946,052	$	5.87	5.84	695,542	$	5.78
$	6.24	-	6.63	827,926	$	6.46	4.93	755,758	$	6.47
$	6.82	-	7.26	1,161,223	$	7.07	7.05	589,230	$	6.89
$	7.40			83,990	$	7.40	9.60	-	$	-
$	9.20			108,580	$	9.20	3.34	108,580	$	9.20
				7,794,623	$	5.30	5.74	4,851,100	$	5.18

Summary of stock-based compensation expense by line item

	Three Months Ended September 30,				Six Months Ended September 30,
	2017		2016		2017		2016
	(In thousands)
Cost of revenues	$	66	$	79	$	113	$	131
Research and development		284		238		551		461
Selling, general and administrative		158		170		322		338
Total	$	508	$	487	$	986	$	930

Schedule of weighted average assumptions

	Three Months Ended September 30,						Six Months Ended September 30,
	2017			2016			2017				2016
	(In thousands)						(In thousands)
Stock Option Plans:
Risk-free interest rate		1.84	%		1.12	%	1.84	-	1.91	%	1.12	-	1.26	%
Expected life (in years)		5.00			5.00				5.00				5.00
Volatility		36.5	%		33.9	%			36.5	%	33.9	-	34.8	%
Dividend yield		—	%		—	%			—	%			—	%
Employee Stock Purchase Plan:
Risk-free interest rate		—	%		—	%			1.04	%			0.38	%
Expected life (in years)		—			—				0.50				0.50
Volatility		—	%		—	%			51.1	%			39.6	%
Dividend yield		—	%		—	%			—	%			—	%