Milliwatt second-harmonic generation in quantum-cascade lasers with modal phase-matching

Milliwatt second harmonic power at 4.45 mm was achieved in InP lattice-matched quantum cascade lasers with monolithically- integrated resonant nonlinear cascades and modal phase-matching. The use of an InP top-cladding layer and high-reflectance coating on the laser back facet enabled high linear laser power and consequently record nonlinear power.