Table 1.

Parameters of the different tunable liquid crystal gratings

Type	w1	w2	w	VDC	VAC	d	Periodic order	h
1	10 μm	10 μm	20 μm	3.7 V	0 V	20 μm	Small	10 μm
	10 μm	10 μm	20 μm	4.0 V	4.5 V	40 μm	Large	10 μm
2	15 μm	15 μm	30 μm	3.9 V	0 V	30 μm	Small	10 μm
	15 μm	15 μm	30 μm	4.2 V	4.7 V	60 μm	Large	10 μm