Supersymmetric optimization of second-harmonic generation in mid-infrared quantum cascade lasers.

We describe a procedure to optimize mid-infrared quantum cascade lasers with respect to the resonant second-order optical susceptibility, based on supersymmetric quantum mechanics. Realization of the optimized potential can be obtained by composition grading of ternary alloys, such as in InGaAs/AlInAs-based structures. The approach yields designs not only with strongly enhanced predicted nonlinear conversion efficiencies, but also with significantly improved modal gain compared with demonstrated devices.