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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0.5～25.4dB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0.2dB,尺寸仅为微米量级。
A new type of tunable optical attenuator (VOA) realized directly by photonic crystal (PC) waveguide is proposed. Based on the tunability of the bandgap in the photonic crystal filled with liquid crystal, the attenuation of the photonic crystal waveguide can be controlled by adjusting the rotation angle of the liquid crystal director. The time-domain finite difference method (FDTD) is used to analyze the principle and structural parameters. The numerical simulation results show that the photonic crystal waveguide filled with liquid crystal can achieve the dynamic attenuation of the luminous flux at 0.5 ~ 25.4dB with the rotation angle of the liquid crystal changed from 0 ° ~ 90 °. The extra loss between the photonic crystal waveguide and ordinary photonic crystal waveguide is only 0.2 dB, the size is only on the order of microns.