Path integral solutions of the Boltzmann-Bloch equation applied to the realistic simulation of GHz-THz superlattice multipliers

We theoretically study the influence of asymmetric scattering processes on the high-frequency response of miniband electrons in a semiconductor superlattice (SSL) under the action of an AC electric field. We show that asymmetric current affects the spontaneous emission and can result in significant enhancement of even harmonics by tuning the interface quality. We model the system using the Boltzmann equation in the path integral form, treated non-perturbatively in the illuminating field by employing local boundary conditions which allow the inclusion of asymmetric relaxation times. Finally, we consider further the deviations from a completely anti-symmetric current-voltage characteristic and analyze the nonlinear response of SSL excited by a Gaussian optical pulse.