5.0 $\mu$m emitting Interband Cascade Lasers with Superlattice and Bulk AlGaAsSb Claddings

Abstract

We present a comparison between interband cascade lasers (ICLs) with a 6-stage active region emitting at 5 $\mu$m with AlSb/InAs superlattice claddings and with bulk Al_0.85 Ga_0.15 As_0.07 Sb_0.93 claddings. Utilizing bulk AlGaAsSb claddings with their lower refractive index compared to the more commonly used AlSb/InAs superlattice claddings, the mode-confinement in the active region increases by 14.4% resulting in an improvement of the lasing threshold current density. For broad area laser and under pulsed excitation, the ICL with AlGaAsSb claddings shows a lower threshold current density of J_th=396 A/cm$^2$ compared to J_th=521 A/cm$^2$ for the reference ICL with superlattice claddings. Additionally, a higher characteristic temperature was obtained for the ICL with bulk claddings. A measured pulsed operation is observed up to 65 C.