Second-harmonic generation in quantum cascade lasers with electric field and current dependent nonlinear susceptibility

The authors demonstrate a quantum cascade laser design with an integrated resonant nonlinearity for second-harmonic generation. Its nonlinear power conversion efficiency is strongly dependent on the injected current density due to an electric field and current dependent nonlinear susceptibility. This dependence produces an observed tenfold increase of the conversion efficiency over the current density range of 2.7 - 7.5 kA ∕ cm 2 . Furthermore, bidirectional lasing at widely different wavelengths is a side effect for this active region design.