GaSb-based Interband Cascade Laser with hybrid superlattice plasmon-enhanced claddings

We present an interband cascade laser (ICL) emitting at 5.2 {\mu}m consisting of an 8-stage active region and a hybrid cladding composed of outer plasmon-enhanced InAs_0.915 Sb_0.085 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/cm^2 in pulsed operation at room temperature. This is the lowest value reported to date for ICLs emitting at wavelengths longer than 5 {\mu}m. We also report close to record value threshold power density of 840 W/cm^2 for ICLs at such wavelengths.