Interband cascade laser emitting >1 photon per injected electron

A 22-stage interband cascade laser with a "W" active region for enhanced gain has exhibited lasing at /spl lambda/=3.0 μm. Threshold current densities are lower than the best reported intersubband quantum cascade laser results at all T up to the maximum lasing temperature of 225 K. At 100 K, output powers up to 430 mW are observed, and the slope of 274 mW/A per facet for high injection levels corresponds to a quantum efficiency of 1.3 photons emitted for every injected electron.