Type-II Quantum Cascade Lasers for 3 to 4 micron IR Sources

In this research, we will investigate and develop a new class of mid-infrared (3-5 pm) diode lasers vVhich was first proposed by the PI. These lasers utilize interband transitions for photon emission in a staircase of Sb-based type-ll quantum wells. In this way, we retain the advantages of cascaded tunneling injection and wavelength tunability, while circumventing the fast phonon scattering loss existed in recently reported intersubband quantum cascade lasers. Therefore, our proposed lasers can have a high radiative efficiency. Additionally, population inversion can be more easily established in our type-ll quantum cascade laser structures with a nearly 100% current injection efficiency. Thus, with these improvements, the proposed type-II quantum cascade lasers promise better performance, higher operating temperature, and larger output power than other structures, e. g, our previously proposed structures, the GalnAs/AllnAs intersubband quantum cascade laser reported by the AT&T group, and the type-II GalnSb!lnAs superlattice laser demonstrated recently by the Hughes croup. The Phase I effort will be directed towards design, MBE growth, characterization and optimization of the novel type-ll InAs/GaInSb/AISb quantum cascade lasers to demonstrate the feasibility of the proposed lasers. High performance diode lasers will be developed in Phase II. The proposed approach will greatly improve overall performance of semiconductor lasers in the spectral range from 3 to 5 um This research should considerabl.s accelerate the realization and commercialization of efficient semiconductor mid-wavelength infrared lasers to meet the potential needs of the huge defense and commercial market