基于透射型几何相位编码超表面的太赫兹波束自由操控  

Free Manipulation of Terahertz Wave Based on the Transmission Type Geometric Phase Coding Metasurface

作　　者：唐小燕 柯友煌 井绪峰 别寻 李晨霞 洪治[2] TANG Xiaoyan;KE Youhuang;JING Xufeng;BIE Xun;LI Chenxia;HONG Zhi(Institute of Optoelectronic Technology,China Jiliang University,Hangzhou 310018,China;Center of Terahertz,China Jiliang University,Hangzhou 310018,China)

机构地区：[1]中国计量大学光学与电子科技学院,杭州310018 [2]中国计量大学太赫兹研究所,杭州310018

出　　处：《光子学报》2021年第1期142-155,共14页Acta Photonica Sinica

基　　金：国家自然科学基金(No.61875179);浙江省自然科学基金(Nos.LZ21A040003,LY20F050007)。

摘　　要：为了实现太赫兹波束的自由操控,基于Pancharatnam-Berry几何相位理论,提出一种多层C型单元结构,实现在目标频率下0到2π的太赫兹波透射传输相位调控。基于广义斯涅耳定律,构建2-bit和3-bit编码超表面,在圆偏振入射条件下,实现透射型太赫兹波束的散射角度调控。采用数字信号处理理论中的傅里叶卷积运算,对不同周期序列的编码超表面进行四位制编码卷积运算,获得新的编码序列,实现对透射太赫兹波散射角度的自由调控。利用多层C型编码超表面单元结构对其进行旋转编码,实现1阶和2阶涡旋相位板,产生不同阶数太赫兹波涡旋光束。In order to realize the free manipulation of terahertz beams,a multi-layer C-type unit structure is proposed to realize the phase control of the transmissionterahertz waves from 0 to 2πat the target frequency based on the Pancharatnam-Berry geometric phase theory.Based on the generalized Snell's law,2-bit and 3-bit coding metasurfaces are constructed.The scattering angle of the transmissive terahertz beam can be controlled with the incidence of circular polarization wave.By using the Fourier convolution operation in the digital signal processing theory,the four-bit encoding convolution operation is performed on the coding metasurfaces of different periodic sequences to obtain a new coding sequence and realize the free adjustment of the transmission angle of the terahertz wave.The multi-layer C-encoded metasurface unit structure is used to perform rotary encoding to realize the 1st and 2nd order vortex phase plates and generate different orders of terahertz wave vortex beams.

关 键 词：电磁波 超表面 太赫兹波 傅里叶卷积 几何相位 散射 

分 类 号：O43[机械工程—光学工程]