A customized terahertz time-domain spectroscopy system for phase-resolved measurements of active semiconductor quantum devices

纳米电子学和量子光电子学器件，如量子级联激光器、半导体量子井光探测器、半导体光放大器等，其外部性能受其内部工作原理的制约，如模式增益、光损耗、自由载流子吸收、载流子输运等。如果没有探测这些关键参数的实验手段，导致设备性能低于平均水平的主要机制充其量仍是推测。该合同为采购所需的元件和仪器以及现有的锁模钛宝石激光器提供了必要的支持，以完成太赫兹时域光谱分析(THz-TDS)系统。THz-TDS系统将被用来对具有金属-金属波导的太赫兹量子级联激光器的激光发射进行温度相关、相分辨、时间分辨的测量。这个家庭集成的系统将是一个非常通用的工具，可以用于不同的研究目的。对于申请人正在进行的半导体量子光电子器件研究项目来说，建议的系统尤其是不可或缺的工具。它将为我们在以下方面的研究提供重要的能力：1)太赫兹量子级联激光器的发展和表征；2)量子半导体异质结内部动态过程的研究；3)太赫兹量子级联激光器高温高功率运行的优化；4)基于半导体量子结构的太赫兹放大器和太赫兹探测器的探索。它将极大地利用我们在开发用于太赫兹成像、生物和环境传感应用的高性能半导体元件方面的研究成果。此外，它还将有助于将我们的研究扩展到纳米技术和纳米电子器件等新领域。建议的系统不仅适合最苛刻的研究应用，而且对我们的研究生和其他HQP来说是一个很好的教学工具。这种太赫兹-时间域光谱学系统的使用将为我们工程专业的本科生和研究生提供更多的研究和教育机会。

The external performance of nanoelectronic and quantum optoelectronic devices such as quantum cascade lasers, semiconductor quantum well photodetectors, semiconductor optical amplifier, etc, is governed by their inner workings as described by modal gain, optical loss, free carrier absorption, carrier transport. Without an experimental means of probing these crucial parameters, the chief mechanisms responsible for sub par device performance remain speculative at best. This award provides essential support for the acquisition of needed components and instruments, in combination with an existing mode-lock Ti:Sapphire laser, to complete a terahertz time-domain spectroscopy (THz-TDS) system. The THz-TDS system will be used to carry out temperature-dependent, phase-resolved, time-resolved measurements of lasing emission from a terahertz quantum cascade laser with a metal-metal waveguide. This home-integrated system will be a very versatile and enabling tool for different research purposes. The proposed system is particularly an indispensible tool for the applicant's ongoing research projects on semiconductor quantum optoelectronic devices. It will provide vital capabilities to our research on: 1) development and characterization of THz quantum cascade lasers; 2) investigation of internal dynamic processes of quantum semiconductor heterostructures; 3) optimization of terahertz quantum cascade lasers for high-temperature and high power operation; 4) exploration of terahertz amplifiers and terahertz detectors based on semiconductor quantum structures. It will significantly leverage our research efforts in developing high-performance semiconductor components for THz imaging, bio- and environmental sensing application. In addition, it will help extend our research into new areas such as nanotechnology and nanoelectronic devices. Not only does the proposed system fit the most demanding research application, it is a great teaching tool for our graduate students and other HQP. The availability of this THz-time-domain spectroscopy system will enrich the research and education opportunities to our undergraduate and graduate students from the engineering programs.