Quasiphase matching of second-harmonic generation in quantum cascade lasers by Stark shift of electronic resonances

Abstract

We demonstrate a quasiphase matching scheme for second-harmonic generation in quantum cascade lasers with integrated resonant nonlinearity. Modulation of the nonlinear susceptibility is achieved by the periodic modulation of the bias voltage along the ridge waveguide leading to a periodic shift of electronic resonances and a change in the electron population in different energy levels. An up to tenfold enhancement of the conversion efficiency is observed. This technique is applicable to any resonant nonlinear optical process in quantum wells.