Interband cascade lasers emitting at 4.6–6.1 µm

We report interband cascade lasers exhibiting improved performance in the λ = 4.6-6.1 μm spectral range. For pulsed operation at 300 K, the threshold current density of a broad area device emitting at λ ≈ 4.8 μm is 220 A/cm
²
, while its external differential quantum efficiency per stage is 33%.