Type-II Quantum Cascade Lasers for 8-12 Micron IR Sources

In the proposed research, we will investigate a new class of long wavelength-IR (8-12 um) lasers which was first suggested by the PI in 1994. These lasers are based on cascaded type-II quantum wells. They maintain the electron recycling advantage of the recently reported quantum cascade laser, while circumvent its limitations. Not only can a population inversion be easily created with a nearly 100% current injection efficiency, but also the nonradiative loss from the optical phonon scattering can be greatly suppressed. They promise lower threshold current, higher operating temperature. higher output power, and more tunability than other reported mid-R lasers, e. g., the GaInAs/AlInAs quantum cascade laser demonstrated by the AT&T group. The Phase I effort will be directed towards simulation and modeling of the novel Type-II QC lasers. the optimization of MBE growth of InAs/GaInSb/AlSb heterostructures, and the realization of optically pumped devices. The development of electrically pumped laser diodes and the optimization of the materials and devices for high power operation at room temperature will be the primary objectives of the Phase II.