【作者】 陈金林；

【导师】 孙军强；

【作者基本信息】 华中科技大学 ， 光学工程， 2009， 博士

【摘要】 THz波在成像技术、材料检测、生命科学以及高速通信等诸多领域都有着重要的应用，目前正成为研究的热点。基于双频激光器的光子混频法能在室温下产生可调谐的连续THz波，为THz产生的重要手段。光子混频THz源具有两个核心技术——稳定双频激光器和高速光电探测器。本文围绕这两个方面对光子混频THz源的核心技术进行了详细的理论和实验研究，另外，作为探测器研究的延伸，本文还对硅基高响应度探测器进行了设计和研究，具体内容如下：(1)研究了光纤激光器的滤波器件——光纤布拉格光栅；分析了相移均匀光栅的透射谱特性及其在双波长单纵模激光器中的适用性：设计和制作了新颖的双π相移啁啾光纤光栅，实现了波长间隔为8nm的双波长窄线宽滤波特性。(2)从理论上分析了THz拍频和双波长单纵模掺铒光纤激光器；讨论了THz拍频形成的原理和条件，推导了THz拍频的自相关迹；研究了双波长单纵模掺铒光纤激光器的实现机理，并重点分析了掺铒光纤激光器的频率烧孔对双波长产生的影响以及饱和吸收体的窄带滤波功能对单纵模实现的重要作用。(3)对双波长单纵模掺铒光纤激光器和THz拍频进行了实验研究；对光纤激光器分别进行了单纵模、多波长和双波长单纵模的实验；实现了稳定的频率相差1THz的双波长单纵模激射；利用自相关仪对THz拍频进行了观察，成功获得了1THz的拍频信号。(4)理论研究了两种高速光电探测器——超短载流子寿命光电导和单传输载流子探测器(UTC-PD)；分析了半导体光电探测器的基本理论和计算模型；推导了一维半导体光电导的解析解；采用商用软件COMSOL对一维和二维光电导进行了数值模拟；设计和分析了一种超短载流子寿命UTC-PD，该器件结合了UTC-PD和超短载流子寿命光电导的优点，克服了光电导高暗电流和UTC-PD慢扩散过程的限制。(5)理论和实验研究了两种高响应度光电探测器——谐振腔增强型(RCE)探测器和纳米柱微弱光探测器；设计和分析了双腔RCE探测器，该探测器具有高量子效率和窄带的探测谱；设计了新颖的纳米柱微弱光探测器，该探测器不仅具有很高的内部增益，而且克服了雪崩二极管(APD)高偏置电压和热载流子串扰等缺点；采用商用软件DESSIS对纳米柱探测器进行了详细的理论分析和数值模拟；同时对其进行了制作设计和实验，研究了核心工艺，并完成了部分制作工艺。更多还原

【Abstract】 THz-wave is receiving intensive research interest due to its broad applications inimaging technology, material analysis, biological science and ultra-high speedcommunications. Photomixing with dual-frequency lasers, which is able to generatetunable CW THz-wave, becomes an important method for THz generation. The keytechnologies of THz generation by photomixing are stable dual-frequency lasers and highspeed photodetectors, which are theoretically and experimentally investigated. In addition,silicon-based high responsivity photodetectors are also studied as an extension to highspeed photodetectors. The detailed content is as follows:(1) Fiber Bragg gratings (FBG) are studied as wavelength filters for fiber lasers.The transmission spectra of phase-shifted uniform FBGs are investigated, and thefeasibility of its applications in the dual-wavelength single-longitudinal-mode (SLM)lasers is discussed. A novel dual-π-phase-shifted chirped FBG, which has a dual-channelnarrow-linewidth transmission spectrum with 8nm wavelength spacing, is designed andfabricated.(2) THz optical beating and dual-wavelength SLM erbium doped fiber lasers(EDFL) are theoretically studied. The principles and conditions of THz beat-notegeneration are discussed, and the autocorrelation trace of THz beat-notes in anautocorrelator is theoretically deduced. The mechanism for dual-wavelength SLM EDFLis studied. The influence of the spectrum hole-burning of erbium-doped fiber lasers ondual-wavelength lasing is analyzed, and the influence of the narrow-band filtering of thesaturable absorber on SLM oscillation is also analyzed.(3) Dual-wavelength SLM EDFL and THz optical beating are experimentallystudied. SLM, multiwavelength, and dual-wavelength SLM performance of the EDFL isexperimented. Stable dual-wavelength SLM EDFL is achieved with the frequency spacingof 1 THz. 1 THz beat-note is also successively observed with the help of an autocorrelator.(4) High speed photodetectors including photoconductors with ultrashort carrierlifetime and uni-traveling-carrier photodiodes (UTC-PD) are theoretically studied. Thetheoretical basis and numerical models of semiconductor photodetectors are analyzed. Theanalytical expressions for 1D photoconductor are deduced, and both 1D and 2Dphotoconductors are numerically simulated by the commercial simulation tool COMSOL.A special UTC-PD based on materials of ultrashort carrier lifetime is designed and analyzed, which takes advantage of the merits of both UTC-PD and photoconductors withultrashort carrier lifetime, but solves the problems of large dark current ofphotoconductors and slow diffusion process of UTC-PDs.(5) High responsivity photodetectors with resonant cavity enhancement (RCE) andnano-pillar are theoretically and experimentally studied. A special double-cavity RCEdetector is designed and analyzed, which carries high quantum efficiency and narrow-banddetection spectrum. A novel nano-pillar detector is invented for weak light detection,which not only has very high internal gain, but also overcomes the shortcomings ofavalanche photodiodes (APD), such as high bias voltage, hot carrier crosstalking, etc. Thenano-pillar detector is theoretically analyzed and numerically simulated by the commercialsemiconductor simulation software DESSIS. The process flow is designed, the keyprocess technologies are studied, and parts of the process are finished.更多还原