为了制得既能够提供黑色同时又具备高透过率的光阀，本文制备了一种能在反射态和透明态之间切换的主动电场可控性液晶光阀。该光阀主要选用3种偶氮类二向色性染料掺杂螺距位于红外区的胆甾相液晶，并详细地研究了螺距对液晶光阀电光性能的影响。实验结果表明：随着螺距的增大，Vth、Vsat和ton均逐渐减小，其中，最大的Vth和Vsat分别仅为6 V和20 V左右，ton也仅为0.878 ms，并且该薄膜的透过率在电场的作用下可达80%以上。因此，所制备的DDCLC薄膜既满足了透明显示面板高透过率的要求，又提高了其能见度。

To achieve a light shutter with both high transmittance and perfect black, a kind of electrically controllable active liquid crystal light shutter was successfully fabricated where the reflection and transparent states can be readily switched on demand.The light shutter was based on three commercially available azobenzene-dichroic dye-doped cholesteric liquid crystals (DDCLC) with the pitch designed in the range of infrared region, and the effect of cholesteric pitch on their electro-optical characteristics was investigated in detail.Experimental results showed that the Vth, Vsatand ton were decreased with the increase of pitch, and among the samples the maximum Vth, Vsat and ton were only about 6 V, 20 V and 0.878 ms, respectively .Moreover, the transmittance of DDCLC films can reach more than 80%.Therefore, the proposed DDCLC films meet the requirements of the transparent display panel with high transmittance and visibility.