CAREER: Development of high-performance terahertz intersubband lasers

本研究的目的是研制基于GaAs/AlGaAs量子级联超晶格的太赫兹辐射半导体激光源。第一个目标是实现可以在室温以上工作的激光器，这是目前不存在的。该方法是利用新的设计方法的量子级联结构中的温度鲁棒电子输运。第二个目标是演示第一个基于空穴的量子级联激光器，并研究半导体价带中的空穴-空穴子带间输运。基于空穴的子带间激光器和探测器将允许辐射的表面垂直耦合，并提高量子效率。其智力价值在于量子级联半导体超晶格的载流子输运的新方案。对于基于电子的设计，将利用无注入器和散射辅助注入方案，预计这些方案比目前使用的共振隧穿注入方法更具温度鲁棒性。对于基于空穴的设计，将探索轻空穴和重空穴之间的辐射跃迁，使光在表面法线方向上发射。室温半导体太赫兹激光器将填补不发达的太赫兹光谱的关键空白，在与健康，医学和安全相关的应用中。这项研究的成果将使低成本和紧凑的仪器的太赫兹传感和光谱学的化学和生物物种，如药物，爆炸物，疫苗，蛋白质，药物化合物和太赫兹成像的疾病诊断以及远程筛选国防和安全的发展。该项目将导致在本科层次的跨学科教育和研究的机会。在社区一级，将在为小学/中学生举办的年度光学讲习班上介绍光子学和量子力学概念。

The objective of this research is to develop semiconductor laser sources of terahertz radiationbased on GaAs/AlGaAs quantum-cascade superlattices. The first goal is to realize lasers that can operate above room-temperature, which do not exist presently. The approach is to utilize new design methodologies for temperature-robust electron transport in quantum-cascade structures. The second goal is to demonstrate the first hole-based quantum-cascade laser and investigate hole-hole intersubband transport in valence band of semiconductors. Hole-based intersubband lasers and detectors will allow surface-normal coupling of radiation with enhanced quantum efficiencies.The intellectual merit is in new schemes of carrier transport for quantum-cascade semiconductor superlattices. For electron-based designs, injectorless and scattering-assisted injection schemes will be utilized that are expected to be more temperature robust than the presently used resonant-tunneling injection methods. For hole-based designs, radiative transitions between light and heavy holes would be explored that enable light emission in the surface-normal direction.Room-temperature semiconductor terahertz lasers will fill a critical gap for the underdeveloped terahertz spectrum, in applications related to health, medicine and security. Outcomes of this research will enable development of low-cost and compact instruments for terahertz sensing and spectroscopy of chemical and biological species, such as drugs, explosives, vaccines, proteins, pharmaceutical compounds, and terahertz imaging for disease diagnosis as well as remote screening for defense and security. The project will lead to interdisciplinary educational and research opportunities at the undergraduate level. At the community level, concepts in photonics and quantum-mechanics would be introduced in an annual optics workshop for elementary/ middle-school students.