双锥面轴棱锥产生长无衍射距离的太赫兹贝塞尔光束  

Terahertz Bessel Beams with Long Non-Diffracting Distance Generated by Biconical Axicon

作　　者：余京京 任姣姣 张丹丹[1,2,3] 张霁旸 薛竣文[3] 李丽娟 韩旭 Yu Jingjing;Ren Jiaojiao;Zhang Dandan;Zhang Jiyang;Xue Junwen;Li Lijuan;Han Xu(Key Laboratory of Optical Control and Optical Information Transmission Technology,Ministry of Education,Changchun University of Science and Technology,Changchun 130022,Jilin,China;School of Opto-Electronic Engineering,Changchun University of Science and Technology,Changchun 130022,Jilin,China;Zhongshan Inatitute of Changchun University Qf Science and Technologw,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7期218-227,共10页Acta Optica Sinica

基　　金：吉林省科技发展计划(20220508032RC);中山市第二批社会公益和基础研究项目(2022B2012)。

摘　　要：为了克服传统轴棱锥产生太赫兹贝塞尔光束无衍射距离短的局限,设计了一种双锥面轴棱锥结构。基于几何光学理论对双锥面轴棱锥产生太赫兹贝塞尔光束的原理进行了分析,并对太赫兹贝塞尔光束的无衍射特性和双锥面轴棱锥顶点对齐误差对无衍射特性的影响进行了理论和仿真计算分析。同时,采用透射式太赫兹时域光谱系统对双锥面轴棱锥的功能进行了实验验证。仿真和实验结果表明:太赫兹波经过锥面底角为γ_(2)=20°、γ_(1)=15°的双锥面轴棱锥后能够产生110 mm无衍射距离的太赫兹贝塞尔光束,相较于传统轴棱锥,无衍射距离增加了82.63 mm;无衍射距离随着锥形底面角度的增加而增大。Objective This study designs a biconical axicon to overcome the limitation of a short non-diffraction distance of terahertz Bessel beams generated by a traditional axicon.The traditional axicon is widely used to generate terahertz Bessel beams because of its simple structure and high conversion efficiency.However,when the radius of the incident terahertz wave is fixed,the non-diffracting distance of the terahertz Bessel beam is inversely proportional to the base angle and refractive index of the axicon.At present,the materials used to make terahertz lenses are mostly high-density polyethylene(HDPE),and the refractive index changes litle with the frequency of the terahertz wave.Most studies increase the non-diffracting distance of terahertz Bessel beams by reducing the base angle of the axicon.However,the small-angle axicon is prone to produce errors in the processing process,which affects the quality of terahertz Bessel beams.Hence,the traditional axicon has certain limitations in generating terahertz Bessel beams with a long non-diffracting distance,which restricts the application of terahertz Bessel beams in some fields such as large depth-of-focus imaging and nondestructive testing.Therefore,on the basis of the traditional axicon,we design a biconical axicon with a simple structure,which does not require complex optical path adjustment to generate terahertz Bessel beams with a long non-diffracting distance.Methods The theory of geometric optics is used to analyze the principle of generating terahertz Bessel beams by the biconical axicon and derives the expression of the non-diffracting distance of terahertz Bessel beams.Then,the optical field distribution of the terahertz wave after passing through the biconical axicon is analyzed with the integral theory of diffraction.The finite-difference time-domain method is employed to simulate and analyze the transmission characteristics of terahertz Bessel beams and the influence of different processing erors on the transmission characteristics.Finally,the function of

关 键 词：物理光学 双锥面轴棱锥 太赫兹贝塞尔光束 无衍射距离 太赫兹时域光谱系统 

分 类 号：O436.1[机械工程—光学工程]