物理学报2016，Vol.65Issue(3)：036803-1-036803-12,12.DOI:10.7498/aps.65.036803
基于光导微探针的近场/远场可扫描太赫兹光谱技术∗
Near-field and far-field scanning terahertz sp ectroscopy based on photo conductive microprob e
摘要
Abstract
Recently, terahertz radiation has been a branch of cutting-edge science and technology involving many fields such as public security, military defense and national economy. In the past, far-field measurements were widely carried out based on terahertz time-domain spectroscopy. But the spatial resolution is limited by far-field diffraction effect. In order to break diffraction limit and gain sub-wavelength spatial resolution in terahertz frequency region, a series of near-field detection methods came into being, such as confocal microscopy, using an aperture, guided mode, scattering, direct detection in the near-field, etc. Each method has its own advantages and disadvantages. Using the photoconductive-antenna tip is one of the direct detection methods and it delivers the possibility of near-field measurements of terahertz waves. In this method, the photoconductive-antenna tip is a tapered photoconductive tip probe. So it can be close enough to the sample surface and receive the near-field signal on the basis of principle of photoconductivity. In this way, high spatial resolution can be gained. In this article, we introduce our recent progress of near-field and far- field scanning terahertz spectroscopy system with photoconductive-antenna in detail. Firstly, we analyze and summarize the near-field detection methods that have been developed in these years. And then, using the femtosecond laser whose center wavelength is 800 nm and the photoconductive-antenna tip detector coupled with fiber, we construct fiber near-field/far-field scanning terahertz spectroscopy (N/F-STS). The frequency bandwidth is in a range from 0.2 THz to 1.5 THz and the terahertz spot is circular and uniform indicated by performance test. Also the amplitude and phase of the terahertz field are recorded simultaneously. It has the ability to perform three-dimension scan in various experiment conditions conveniently. Finally, we introduce the real applications in our laboratory. N/F-STS can be used to scan spatial electric distribution in three dimensions and test the spectral properties in terahertz range like other traditional far-field methods. Nevertheless, the most importantly, N/F-STS is used to scan the terahertz near-field of samples, such as terahertz surface plasmon polaritons, etc. The presented method thus is useful in some application areas, such as metamaterials, graphene, surface plasmons, waveguide transmission, near-field imaging, biological test, and chip inspection.关键词
太赫兹近场/可扫描Key words
terahertz near field/scanning引用本文复制引用
许悦红,张伟力,张学迁,王球,田震,谷建强,欧阳春梅,路鑫超,张文涛,韩家广..基于光导微探针的近场/远场可扫描太赫兹光谱技术∗[J].物理学报,2016,65(3):036803-1-036803-12,12.基金项目
国家重点基础研究发展计划(批准号:2014CB339800)、国家自然科学基金(批准号:61427814,61138001,61205098,61422509)、广西科学研究与技术开发项目(批准号:1598017-1)和“广西特聘专家”专项经费资助的课题.* Project supported by the National Basic Research Program of China (Grant No.2014CB339800), the National Natural Science Foundation of China (Grant Nos.61427814,61138001,61205098,61422509), the Scientific Research and Technology Development Projects of Guangxi, China (Grant No.1598017-1), and the Special Fund of“Guangxi Distinguished Experts”of China （批准号:2014CB339800）
