CAREER: Development of high-performance terahertz intersubband lasers

Lehigh University, Bethlehem PA

Investigators

Abstract

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.