High power quantum cascade lasers for terahertz applications

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The objective of this program is to develop single-mode terahertz semiconductor lasers emitting more than hundred milliwatts of optical power in continuous-wave operation at liquid-nitrogen temperature, which is two orders of magnitude higher than that demonstrated previously. The gain medium will be comprised of GaAs/AlGaAs quantum-cascade heterostructures. Such narrow-band terahertz sources have applications in areas as diverse as radio-astronomy, chemical and biological sensing, and imaging and spectroscopy for identification of concealed weapons, drugs, and explosives. The intellectual merit is in the use of novel waveguide architectures that combine techniques from microwave engineering with those of infrared distributed-feedback lasers. Phased-array antenna structures will be incorporated into semiconductor microcavities with the embedded quantum-cascade gain medium, made possible owing to the unique properties of terahertz radiation. A potentially transformative impact on the field of terahertz science and technology is envisioned by bringing terahertz quantum-cascade lasers out of the mold of research laboratories, to a situation where practical instruments could be built for important applications.The broader impacts are in providing education in the areas of nanophotonics, quantum-electronics, microfabrication, and terahertz technology to graduate and undergraduate students within a research environment. Elements of research will be incorporated into a new course on nanophotonics, and will also be showcased to create scientific interest among high-school students through participation in outreach activities. A program is in place to actively involve undergraduate students in the terahertz research activities in the laboratory. New research collaborations in the area of terahertz applications will be pursued across different institutions.