Optimization of active regions in midinfrared lasers

Abstract

The ideal performance of bulk, quantum well, and superlattice active regions for III-V interband midinfrared lasers are compared according to the maximum net gain per unit current density. Based on this figure of merit, which is appropriate for high-power as well as near-threshold operation, InAsSb quantum well active regions should have an order of magnitude lower threshold current than bulk InAs at room temperature. Optimized four-layer superlattices based on the InAs/GaInSb material system, however, should have two to ten times lower threshold currents than the quantum well active regions. Optimal thicknesses for these active regions were evaluated assuming a separate confinement region design. For the four-layer superlattices the optimal thickness is substantially thinner than has been commonly grown: 3 periods rather than 40 periods. © 1999 American Institute of Physics.