Mid-infrared interband cascade lasers operating at ambient temperatures

We discuss the state-of-the-art performance of interband cascade lasers emitting in the 3–5 μm spectral band. Broad-area devices with five active stages display pulsed threshold current densities as low as 400 A cm −2 at room temperature. Auger decay rates are extracted from the analysis of threshold current densities and differential slope efficiencies of nearly 30 lasers, and found to be significantly lower than was anticipated based on prior information. New designs also produce ICLs with room-temperature internal losses as low as ≈6 cm −1 . The combination of these advances with improvements to the processing of narrow ridges has led to the fabrication of a 4.4-μm-wide ridge emitting at 3.7 μm that lased to 335 K in continuous mode. This is the highest continuous-wave (cw) operating temperature for any semiconductor laser in the 3.0–4.6 μm spectral range. A 10-μm-wide ridge with high-reflection and anti-reflection facet coatings produced up to 59 mW of cw power at 298 K, and displayed a maximum wall-plug efficiency of 3.4%.