为了研究带宽可调型光学滤波器，采用对手性液晶膜施加电压的方法，对手性液晶布喇格反射带宽随外加电场的变化规律进行了分析和测量。实验结果表明，在外加电场到达一定的阈值后，液晶分子要旋转一定的角度；在外加电场和液晶盒边界条件的共同限制下，手性液晶的螺距在螺旋轴方向上形成了梯度变化，造成了手型液晶布喇格反射带宽的加宽，且反射带宽随外加电压的增加而增加，以此可制成带宽可调型光学滤光片。

In order to study adjustable-bandwidth optical filters,the variation of Bragg reflection bandwidth induced by electric field in cholesteric liquid crystal(CLC)was measured and analyzed. Experimental results showed that field-induced reorientation might happen when the applied electric field reached a threshold value. The pitch of CLC became gradient along the axis under the combine restriction of applied electric field and boundary condition of liquid crystal cell and the bandwidth was broadened with the input voltage,based which adjustable optical filter can be manufactured.