High-Temperature Terahertz Quantum Cascade Lasers

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

0500925 Hu The proposed research seeks to develop terahertz quantum-cascade lasers (THz QCLs) that operate at high temperatures. Specifically, by end of the proposed three-year period, the principal investigator envisions the development of THz QCLs that can operate at temperatures above 200 K, so that they can be conveniently cooled by thermoelectric coolers. Such a development will have a significant impact on the science and technologies in THz frequencies, where potential applications are promising in detection of chemical and biological agents, imaging for medical and security applications, astrophysics, plasma diagnostics, remote atmospheric sensing and monitoring, high-bandwidth free-space communications, and ultrahigh-speed signal processing. This project is highly challenging, since at 200 K, the thermal energy is greater than the photon energy, , at frequencies below 4.2 THz. Towards this goal, the PI has identified that maintaining population inversion at high temperatures is the key issue. Based on a thorough analysis, the PI has developed a strategy to systematically address this issue. Intellectual merit of the proposed activity: The project will involve a considerable amount of design effort, as the number of quantum wells will be large and their combination will likely be complicated. If an isolated quantum well can be viewed as a one-dimensional "artificial atom", then a multiple quantum-well (MQW) structure is an "artificial molecule". This project is nothing short of designing and making such artificial molecules that perform the desired function of THz lasers. The principal investigator has one of the best track records in the field and has access to all the necessary facilities to carry out the research activities. Broader impacts resulting from the proposed activity: Following the recent breakthrough, the principal investigator has been invited to give invited/plenary/keynote talks at many prestigious conferences. The work has also been reported in media for broad communities such as Technology Review and NPR Market Place. Through collaborations, the THz lasers developed in the PI's group have helped to enhance infrastructures at other institutions in THz-related activities by adding a crucial enabling component. The principal investigator has incorporated elements in the research project into a graduate course in solid-state physics and a undergraduate core course Signals and Systems. He plans to further this integration of teaching and research during the project. Furthermore, effort has been made and will be continuingly made to involve members from underrepresented groups and undergraduate students in the research activities.