Recent advances in type-II interband cascade lasers

Abstract

Interband cascade (IC) lasers are a new class of mid-IR light sources, which take advantage of the broken-gap alignment in type-II quantum wells to reuse electrons for sequential photon emissions from serially connected active regions. Here, we describe recent advances in InAs/GaInSb type-II IC lasers at emission wavelengths of 3.6 - 4 micrometer; these semiconductor lasers have exhibited significantly higher differential quantum efficiencies and peak powers than previously reported. Low threshold current densities (e.g., approximately 56 A/cm 2 at 80 K) and power efficiency exceeding 9% were observed from a mesa-stripe laser in cw operation. Also, these lasers were able to operate at temperatures up to 250 K in pulsed mode and to 120 K in cw mode. We observed from several devices at temperatures above 80 K a slope efficiency of approximately 800 mW/A per facet, corresponding to a differential external quantum efficiency of approximately 500%. Peak optical output powers exceeding 4 W per facet were observed from several type-II IC laser at 80 K.