提出一种直接用光子晶体(PC)波导实现的新型可调光衰减器(VOA)。基于填充液晶的光子晶体方向带隙的可调节性,通过调节液晶指向矢的旋转角实现对光子晶体波导衰减量进行控制。采用时域有限差分法(FDTD)对其原理和结构参量进行了分析。数值模拟结果表明,随着液晶旋转角从0°～90°改变,填充液晶的光子晶体波导可以实现光通量在0.5～25.4 dB的动态衰减,它插入到普通光子晶体波导之间的额外损耗只有0.2 dB,尺寸仅为微米量级。

A novel variable optical attenuator (VOA) based on the photonic crystal (PC) waveguide infiltrated with liquid crystals is demonstrated. The PC waveguide decrement is controlled by adjusting rotation angle of the liquid cyrstals orientation vector. And the VOA properties are numerically investigated by using the finite difference time domain (FDTD) method. Numerical simulation shows that the attenuator in the PC waveguide can be changed based on the orientation of liquid crystals by adjusting the applied field. Furthermore, the attenuator lies in 0.5～25.4 dB with rotation angle of the liquid crystals varying from 0° to 90°, the insertion loss is less than 0.2 dB, and the size is in micron dimension.