HIGH-PERFORMANCE INTERBAND CASCADE LASERS FOR λ = 3-4.5 μm

Abstract

We discuss the single-mode performance characteristics of midwave-infrared interband cascade lasers. Broad-area devices with 5 active stages display pulsed threshold current densities as low as 375 A/cm2 and threshold power densities as low as 920 W/cm2 at room temperature, owing in part to the suppression of Auger recombination. Narrow ridges were processed using optical lithography to incorporate a periodically-corrugated pattern into the sidewalls. The corrugations are intended to suppress lasing in higher-order lateral modes, and also provide a 4th-order grating for distributed feedback. A corrugated-sidewall device operating at T = -20° C produced more than 46 mW of cw output in a single spectral mode, with a peak wallplug efficiency of 7.6%. The device maintains single-mode operation at current densities up to 10 times the lasing threshold, and the single-mode tuning range is 26 nm if both current and temperature are varied. Another device operating at -23°C produces up to 31 mW of single-mode power in the 3.3142-3.3164 μm range that spans several of the strongest absorption signature lines for methane.