基于液晶缺陷层的一维可调谐光子晶体滤波器研究

从液晶连续体理论出发,用数值方法分析了以向列相液晶为缺陷层的Si/SiO2一维光子晶体滤波器的调谐原理和调谐量与外场的关系.确定出一种滤波带宽小、调谐范围大的滤波器的结构参量.模拟计算结果显示,该滤波器在外加电压为0.955~5 V时的调谐范围为1 600.6~1 499.8 nm,调谐量达到100.8 nm,完全覆盖了C波段,以及S波段和L波段的绝大部分区域.在整个调谐范围内,其3 dB带宽在0.074~0.090 nm之间,带宽的差异小于17.8%.

Optically Tunable Narrowband Filter Using Liquid Crystal Defect in 1-D Photonic Crystal

Based on the theory of liquid crystal continuum,the tuning principle of one dimensional Si/SiO2 photonic crystal embedded in a nematic liquid crystal as a defect layer is analyzed and the relationship between applied voltage and tuning range is studied numerically by using transmission matrix method.The structure parameters of a tunable filter with narrow bandwidth and broad tuning range are determined through simulation computation.The computation results show that the tuning range achieve 100.8 nm between 1 600.6 nm and 1 499.8 nm when the applied voltage varies from 0.955 V threshold to 5 V saturation.The obtained tuning range covers telecommunication C band and almost S and L band.FWHMs(full width at half maximum) of the transmission peaks are between 0.074 nm and 0.090 nm,and the differences of bandwidths less than 17.8 percent.