GaSb-based interband cascade laser with hybrid superlattice plasmon-enhanced claddings

We present an interband cascade laser (ICL) emitting at 5.2 µm consisting of an 8-stage active region and a hybrid cladding composed of outer plasmon-enhanced InAs0.915Sb0.085 and inner InAs/AlSb superlattice claddings. The hybrid cladding architecture shows an increase in mode confinement in the active region by 11.2% according to the simulation. This is a consequence of a significantly lower refractive index of plasmon-enhanced claddings. The threshold current density is 242 A/cm2 in pulsed operation at room temperature. This is the lowest value reported to date for ICLs emitting at wavelengths longer than 5 µm. We also report close to record value threshold power density of 840 W/cm2 for ICLs at such wavelengths.