太赫兹导模谐振滤波器的自动化设计方法研究  

Automated Design Study of Guided-Mode Resonance Filters Working at Terahertz Frequencies

作　　者：邵天宇 谷建强[1] 师文桥 Shao Tianyu;Gu Jianqiang;Shi Wenqiao(Center for Terahertz Waves,School of Precision Instrument and Opto-Electronics Engineering,Key Laboratory of Optoelectronic Information Technology,Ministry of Education,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学太赫兹研究中心,精密仪器与光电子工程学院,光电信息技术教育部重点实验室,天津300072

出　　处：《中国激光》2021年第20期170-179,共10页Chinese Journal of Lasers

基　　金：国家自然科学基金(61975143,62027820,61622505)。

摘　　要：太赫兹窄带滤波器是太赫兹波段无线通信、高分辨光谱分析和被动式安检成像等技术设备中不可或缺的功能器件,而介质光栅中的导模谐振(GMR)效应是实现高品质因数太赫兹窄带滤波器的重要方法。目前,常使用严格耦合波分析法(RCWA)描述光栅的辐射特性并结合粒子群算法(PSO)优化结构参数来设计导模谐振滤波器(GMRF)。然而,该方法的建模过程复杂并且不能设计广义的超材料光栅。本文提出一种新的自动化设计方法,使用电磁仿真软件CST和PSO相结合设计导模谐振滤波器,采用含有惩罚项的目标函数对滤波器参数进行优化。运用该设计方法分别设计了中心频率位于0.65 THz的一维矩形光栅带阻滤波器和中心频率位于0.6 THz的二维偏振无关的超材料导模谐振滤波器,并通过光刻和反应离子刻蚀加工所设计的高阻硅光栅,分别测量了光栅在TE偏振态下的正入射光谱和入射角为4°、8°的斜入射光谱,谐振的分布和变化规律与仿真结果一致,验证了设计方案的有效性。该研究为太赫兹波段导模谐振器件的研究提供了新的设计方法,并由此推动太赫兹无线通信、光谱分析和被动成像的发展。Objective Terahertz narrowband filters are indispensable functional devices for terahertz wireless communication,high-resolution spectroscopy,and passive security imaging techniques;the guided-mode resonance(GMR)effect in dielectric grating is a promising route for realizing these narrowband filters.The combination of the particle-swarm optimization(PSO)algorithm and rigorous coupled-wave analysis(RCWA)is a widely used method for devising GMR filters.However,Maxwell equations are usually hard to establish and solve when dealing with more complicated gratings,especially for metasurface gratings.This study proposes a novel automated design method that uses the PSO algorithm to invoke the commercial software,CST,to calculate dielectric grating transmission.By adding a"penalty"item in the fitness function,we design a silicon grating with a GMR at 0.65THz and a polarization-independent metasurface grating with a GMR at 0.6THz.The proposed automated design method provides a novel approach for investigating terahertz GMR devices,which may greatly promote the development of terahertz communication,spectroscopy,and passive imaging.Methods Silicon is almost lossless and nondispersive in a terahertz band,making it suitable for narrowband filters.In this study,we set the refractive index of silicon to 3.45,which has been widely used in previous studies.We aimed to design a silicon grating that worked at 0.65THz and avoided absorption from water vapor.The whole design process was completed using MATLAB,where the PSO algorithm was easy to implement and converge.The whole design process began from program initialization and setting the parameters,in which the binary-coded PSO was used conveniently control the parameters’resolution.The fitness function adopted herein comprised two parts:the rootmean-square error between the objective and the calculated transmittance and the penalty item used to limit the central frequency.We used the same PSO frame to invoke an RCWA code and the commercial software CST for calculating the grat

关 键 词：太赫兹技术 导模谐振 粒子群算法 光栅 

分 类 号：O436[机械工程—光学工程]