太赫兹光电导天线电极双层异排列微纳结构研究  

Double-Layer Heterogeneous Micro-Nano Structure of Terahertz Photoconductive Antenna Electrodes

作　　者：夏鹏宇 李全勇 李堂玥[1,2,3] 张悦 谢蕙阳 张丹丹 任姣姣 Xia Pengyu;Li Quanyong;Li Tangyue;Zhang Yue;Xie Huiyang;Zhang Dandan;Ren Jiaojiao(Key Laboratory of Photoelectric Measurement and Optical Information Transmission Technology of Ministry of Education,Changchun University of Science and Technology,Changchun 130022,Jilin,China;School of Optoelectronic Engineering,Changchun University of Science and Technology,Changchun 130022,Jilin,China;Zhongshan Institute of Changchun University of Science and Technology,Zhongshan 528400,Guangdong,China)

机构地区：[1]长春理工大学光电测控与光信息传输技术教育部重点实验室,吉林长春130022 [2]长春理工大学光电工程学院,吉林长春130022 [3]长春理工大学中山研究院,广东中山528400

出　　处：《光学学报》2023年第16期337-343,共7页Acta Optica Sinica

基　　金：吉林省科技发展计划项目(20220508032RC);中山市第九批创新科研团队(GXTD2022010);中山市第二批社会公益和基础研究项目(2022B2012)。

摘　　要：太赫兹光电导天线是一种常用的太赫兹源,但光导材料都有很高的折射率,导致其光电转换效率较低,同时由于存在电场的屏蔽效应,太赫兹辐射功率极易饱和,难以提升。基于表面等离子激元理论,采用时域有限差分方法(FDTD)软件计算仿真了太赫兹波通过柱状金属间隙的增强性能,从改变微纳结构着手以改善太赫兹光电导天线把泵浦激光转换为太赫兹波的转换效率。设计的双侧异排列微纳结构透过率达到90.38%,电场强度达到1.02,是单层微纳结构的185.45%。结果表明,当其他条件相同的情况下,单层正三角形排列的圆柱纳米柱优于其他单层结构,双层异排列微纳结构优于单层微纳结构及其他双层结构。Objective Terahertz(THz)waves are electromagnetic ones with frequencies ranging from 0.1 THz to 10 THz.Due to their high penetration,low photon energy,and high communication capacity,terahertz waves are widely employed and have important applications in broadband communication,medical imaging,nondestructive testing,security,and other fields.However,as how to generate high-quality terahertz waves becomes a major technical problem,the THz frequency band is once called the THz gap.With the rapid development of ultrafast optoelectronics,photoconductive antenna(PCA),a THz source involved in electronics and photonics,can be applied at room temperature,with high frequency of THz wave generation and low requirements for laser pump power,which makes it stand out among other THz sources.However,due to the high refractive index of photoconductive materials,the photoconversion efficiency of THz PCA is low.Meanwhile,due to the shielding effect of electric fields,the THz radiation power is easily saturated and difficult to improve.Methods The radiation power of THz PCA is affected by many parameters,such as current density,bias voltage,selected laser power,and repetition frequency.However,the micro-nano structures can effectively improve carrier mobility to form more obvious local enhancement of electric fields at the interface with LT-GaAs substrate.Therefore,based on the surface plasmas theory,our paper adopts the finite difference time domain(FDTD)method.With the purpose to study the efficiency enhancement of THz PCA,the period and structural parameters of micro-nano structures are calculated and simulated by FDTD software.In simulating THz wave radiation of PCA,the laser irradiates at the gap between the PCA electrodes,which stimulates the transient photocurrent in the substrate.The transient photocurrent is incorporated into the FDTD calculation as the current source,which makes the FDTD algorithm can be employed in semiconductor calculation.Adding a dielectric anti-reflection layer on the substrate surface can increase t

关 键 词：光电导天线 太赫兹 异排列 双层微纳结构 时域有限差分法 

分 类 号：TN383[电子电信—物理电子学]