CAREER: Development of high-performance terahertz intersubband lasers

本研究的目的是研制基于量子级联超晶格的半导体太赫兹光源。第一个目标是实现可以在室温以上工作的激光器，这是目前还不存在的。该方法是利用新的设计方法在量子级联结构中进行温度健壮的电子传输。第二个目标是展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空穴-空穴间的子带输运。基于空穴的子带间激光器和探测器将允许辐射的表面法向耦合，并提高量子效率。智能的优点在于量子级联半导体超晶格的新的载流子传输方案。对于基于电子的设计，将使用无注入器和散射辅助注入方案，预计它们将比目前使用的共振隧道注入方法更具温度稳定性。对于基于空穴的设计，将探索轻孔和重孔之间的辐射跃迁，以实现表面法线方向的光发射。室温半导体太赫兹激光器将填补太赫兹光谱不发达的关键空白，应用于健康、医药和安全领域。这项研究的成果将有助于开发低成本和紧凑的仪器，用于太赫兹传感和化学和生物物种的光谱分析，如药物、炸药、疫苗、蛋白质、药物化合物、用于疾病诊断的太赫兹成像以及用于国防和安全的远程筛查。该项目将为本科生带来跨学科的教育和研究机会。在社区一级，将在为中小学生举办的年度光学讲习班上介绍光子学和量子力学的概念。

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.