超快相干太赫兹波产生与探测关键技术研究

发布时间：2018-12-23 19:39

【摘要】：太赫兹技术从诞生以来经历了一段较长的发展过程，从最初“太赫兹空隙”的提出，直到近年随着超短脉冲激光和低维半导体技术的发展，以超快光电导器件为代表的一系列高性能太赫兹波源和高灵敏度探测器的出现，极大地推动了太赫兹科学技术的飞速发展。随着研究学者们对太赫兹波的深入了解，太赫兹波越来越多的独特性能被人们发现，，如光子能量低、可穿透大部分电介质和非极性材料传播、有很高的时间和空间分辨率、频段范围对应着大量有机分子的转动和振动能级等。太赫兹波的应用领域也由最初的宇宙学、分子光谱学、安全检测、物质鉴别、器件特性研究、生物医药等，逐渐延伸到太赫兹通信、太赫兹雷达等领域。在太赫兹科学技术发展过程中，太赫兹辐射源和探测器的研究一直受到学者们的高度重视。如何高效产生太赫兹波以及对太赫兹信号进行精确有效地探测对太赫兹波科学技术的进一步研究和应用起着至关重要的作用。本文从太赫兹辐射产生与探测出发，对光电导天线产生太赫兹波、空气等离子体产生太赫兹波、自由空间电光取样探测太赫兹波、光电导取样探测太赫兹波等主要的超快相干太赫兹信号产生与探测方法中一些关键技术进行了研究，具体内容包括：（1）研究了光电导天线产生超快相干太赫兹信号过程中，天线电极受损伤情况以及电极间隙之间光斑大小对太赫兹信号产生的影响，并通过改变不同系统参数对太赫兹信号进行了优化，将太赫兹信号频谱覆盖范围由2THz拓展到4THz，时域信号峰峰值提高50%。（2）研究了激光诱导空气等离子体产生超快相干太赫兹波的机理，通过激光诱导空气等离子体的有质动力辐射、四波混频辐射以及外加偏压增强等离子体辐射等方法获得了超快相干太赫兹脉冲信号。（3）研究比较了自由空间电光取样以及光电导取样探测超快相干太赫兹信号的方法，利用自研光电导天线器件初步实现了超快相干太赫兹信号的探测。
[Abstract]:Terahertz technology has experienced a long development process since its birth, from the initial "terahertz gap" to the recent years with the development of ultrashort laser and low-dimensional semiconductor technology. The emergence of a series of high performance terahertz wave sources and high sensitivity detectors, represented by ultra-fast photoconductive devices, has greatly promoted the rapid development of terahertz science and technology. With the further understanding of terahertz waves by researchers, more and more unique properties of terahertz waves have been discovered, such as low photon energy, penetrating most dielectric and non-polar materials, and high temporal and spatial resolution. The frequency range corresponds to the rotation and vibrational energy levels of a large number of organic molecules. The application of terahertz wave has been extended to terahertz communication, terahertz radar and so on from the original cosmology, molecular spectroscopy, safety detection, material identification, device characteristic research, biomedicine and so on. In the development of terahertz science and technology, the research of terahertz radiation sources and detectors has been paid great attention by scholars. How to efficiently generate terahertz wave and how to detect terahertz signal accurately and effectively play an important role in the further research and application of terahertz wave science and technology. Starting from the generation and detection of terahertz radiation, terahertz waves are generated for photoconductive antennas, terahertz waves are produced by air plasma, and terahertz waves are detected by free space electro-optic sampling. Some key techniques in the generation and detection of ultra-fast coherent terahertz signals, such as photoconductive sampling for terahertz waves, are studied. The main contents are as follows: (1) in the process of producing ultra-fast coherent terahertz signal by photoconductive antenna, the damage of antenna electrode and the effect of spot size between electrodes on the generation of terahertz signal are studied. The terahertz signal is optimized by changing different system parameters. The spectrum coverage of terahertz signal is extended from 2THz to 4THZ, and the peak value of time domain signal is increased by 50%. (2) the mechanism of ultra-fast coherent terahertz wave produced by laser induced air plasma is studied, and the mass dynamic radiation of air plasma is induced by laser. Ultra fast coherent terahertz pulse signals are obtained by four wave mixing radiation and external bias enhanced plasma radiation. (3) the methods of detecting ultra-fast coherent terahertz signals by free space electro-optic sampling and photoconductive sampling are studied and compared. The detection of ultra-fast coherent terahertz signals is preliminarily realized by using self-developed photoconductive antenna devices.
【学位授予单位】：中国科学院研究生院（西安光学精密机械研究所）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN820

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