太赫兹波段一维金属线栅的偏振特性研究

Polarization Characteristics of One-Dimensional Metallic Wire-Grating Polarizer in Terahertz Frequency Range

基于时域有限差分法(FDTD)对一维金属线栅结构在0.2～2.6THz波段的偏振特性进行了数值分析,研究了其结构参数如金属占空比、狭缝宽度以及线栅周期对相互垂直的两种偏振模式太赫兹波透射系数的影响。利用光刻和金属膜制备工艺,在1mm厚的高阻硅衬底上淀积了200nm厚的金膜,制成了一系列一维金属线栅结构。利用太赫兹时域光谱系统,实验测量了这些线栅结构的太赫兹透射特性,实验结果与模拟结果规律一致。结果表明:适当设计金属线栅周期,同时满足一定的金属占空比要求,其整体偏振和透射性能能够得到优化。金属线栅结构参数与其太赫兹偏振性能之间的关系为制造太赫兹偏振器提供了参考。

Based on the finite differential time domain（FDTD） method,numerical simulation of polarization characteristics of one-dimensional metallic wire-grating polarizer in the frequency range of 0.2~2.6 THz is carried out.The effects of structural parameters of metallic wire-grid polarizer such as metal duty cycle,the width of slit and the periodicity of wire-grating on the terahertz transmission at two kinds of polarization modes are investigated.With the technique of photolithography and the metal film deposition,a 200-nm-thick gold film is fabricated on a 1-mm-thick high-resistivity silicon substrate.A series of one-dimensional wire-gratings are formed on the silicon substrate.The transmission spectra of the wire-grating polarizer are measured by the terahertz time domain spectroscopy.The numerical simulations based on FDTD method show a good agreement with experimental results.The results show that it is possible to optimize the performance of one-dimensional wire-grating polarizer through reasonable design of structural parameters.This work provides a good reference for the manufacture of terahertz polarizer.