Physics-Based Models for Mid-IR Bismides Semiconductor Lasers

ABSTRACT: The objective of this STTR is to determine the potential of the novel III-V-Bi material system for laser applications for the 3-5m window with the potential of watt-level powers for Air Force applications. This wavelength range is currently inadequately served for CW operation at room temperature by three challenging technologies: i) quantum cascade lasers (QCL), interband cascade lasers (ICL) and AlInGaAsSb based type-I quantum well lasers. The III-V-Bi material can potentially achieve better performance in the full 3-5m regime. Incorporating dilute amounts of Bi atoms in the host material strongly reduces the bandgap extending the accessible wavelength range over existing systems. Also, interaction between Bi-atoms and the host matrix modifies the bandstructure and the density of states of the host material. It changes the hole effective mass, modifies the internal strain, changes the spin-off splitting, perturbs the Bloch character of states and can introduce gaps in the valence-band structure. This could potentially allow for drastic reductions of the Auger and intraband absorption losses that limit the performance of existing lasers. Large scale density functional (DFT) simulations will be employed to extract critical bandstructure parameters and an interface built to input these into Nonlinear Control Strategies SimuLaseTM semiconductor epitaxial design software.; BENEFIT: The strong demand for high quality semiconductor laser systems fordual-use technologies that must satisfy stringent militaryspecifications as well as future state-of-the-art commercialapplications, creates a critical need for a commercial softwarepackage that can leverage a cost effective, fast track to the finallaser product. Future improvements in semiconductor wafer growthquality will require the implementation of improved wafer processingdiagnostics during in-situ growth within MBE and MOCVD systems. Forexample, state-of-the-art MBE growth systems contain multiple chambersdesigned to carry out wafer diagnostics during material growth. Futuremarkets for such a software suite will include individual VCSELs,VCSEL arrays, high-power/brightness VECSELs, better performingsemiconductor optical amplifiers (SOAs), higher slope efficiency edgeemitters (both single mode, broad area and diode bars) etc. Existingsemiconductor material technologies for the 3-5 m mid infrared rangeare severely limited by low gain, high losses, poor beam quality, lowwall-plug efficiencies and, often, the need to operate at cryogenictemperatures. An approach to avoid many of these problems may be foundby adding small amounts of bismuth to the conventional 3-5 micron materials. The mid-IR laser software design development hasseveral potential applications to IRCM, ISR (Intelligence,Surveillance, Reconnaissance): LADAR, 3-D imaging, active illumination imaging inthe mid-wave IR requiring sources that operate as efficiently aspossible and at Watt power levels.