Dual-frequency liquid crystal-polymer grating for fast response optical beam steering

In this study, we propose a liquid crystal (LC) beam deflector by combining dual frequency (DF) nematic LCs with optical micro structures. The total efficiency of up to 81% and 97%, are obtained for the beam steering state and the non-steering state, respectively. Optical micro gratings with fixed spacers are successfully fabricated using laser ablation and soft embossing. A dual frequency driving method is applied to the LC beam steering device for both the switching-on and the switching-off processes. The non-steering state is switched to the beam steering state rapidly with a duration as short as 3.8 ms, and the response time from the beam steering state to the non-steering state is achieved to be 20.5 ms, even when a thick LC layer with thickness of about 10 micron is required. The response behaviour of this LC beam deflector can be further improved with the increase of the driving voltage or/and decrease of the LC thickness, which is very promising in quick response LC applications, such as dynamic lightings, auto-stereoscopic displays, optical communications etc.