Low-threshold interband cascade lasers with power efficiency exceeding 9%

Midinfrared (3.6–3.8 μm) interband cascade lasers based on InAs/GaInSb type-II quantum wells have been demonstrated in the continuous-wave (cw) mode with low-threshold current densities (e.g., ∼56 A/cm2 at 80 K) and power efficiencies exceeding 9%. At a relatively low current of 0.4 A, we observed ∼100 mW/facet of optical power out at 80 K (124 mW at 60 K) from lasers mounted epilayer-side up with uncoated facets. These lasers were able to operate in the cw mode at temperatures up to 127 K. Also, in the pulsed mode, devices lased at temperatures up to 250 K and displayed, at 80 K, a peak power efficiency exceeding 11%.