设计了一种二维液晶调制光子晶体微腔光衰减器。两条二维三角晶格空气孔光子晶体波导由一个光子晶体微腔连接, 在微腔的点缺陷中填充苯乙炔类液晶。通过施加不同电压, 电场诱导液晶取向以改变液晶的折射率, 从而改变光子晶体微腔的谐振波长, 进而实现光传播强度调节。运用时域有限差分方法和平面波展开法分析了二维液晶调制光子晶体微腔光衰减器的光学特性。数值计算结果表明: 对于1.55 μm通信波段, 通过外界电场控制所填充的向列相液晶的方向可以对这种二维液晶调制光子晶体微腔光衰减器实现3.40%～99.58%的可调谐光输出。

A novel variable optical attenuator (VOA) based on the photonic crystal (PC) cavity with liquid crystals is demonstrated. Two photonic crystal waveguides are connected by photonic crystal cavity. The point defect of photonic crystal cavity is filled with phenylacetylene liquid cyrstals. The output of optical attenuator is controlled by adjusting rotation angle of the liquid cyrstals orientation vector. The VOA properties are numerically investigated by using the finite difference time domain (FDTD) method and plane wave expansion method. Numerical simulation shows that the attenuator based the PC cavity can be changed by adjusting the applied field. Furthermore, the attenuator performs output of 3.40%～99.58% at the wavelength of 1.55 μm.