Non-Degenerate Two-Photon Absorption in ZnSe: Experiment and Theory

Abstract

We experimentally and theoretically investigate the non-degenerate two-photon absorption coefficient β(ω1, ω2) in the prototypical semiconductor ZnSe. In particular, we provide a comprehensive data set on the dependence of β(ω1, ω2) on the non-degeneracy parameter ω1/ω2 with the total frequency sum ω1 + ω2 kept constant. We find a substantial increase of the two-photon absorption strength with increasing ω1/ω2. In addition, different crystallographic orientations and polarization configurations are investigated. The nonlinear optical response is analyzed theoretically by evaluating the multiband semiconductor Bloch equations including inter-and intraband excitations in the length gauge. The band structure and the matrix elements are taken an eight-band k•p model. The simulation results are in very good agreement with the experiment.