Temporal pump depletion and self-defocusing of electronic origin in ZnSe at room temperature

Observations of temporal and spatial nonlinear effects in polycrystalline ZnSe at room temperature with nanosecond laser pulses near the bandgap are reported. Temporarily and spatially resolved transmission were measured. Typical results for the temporal pump depletion and for self-focusing for a polycrystalline ZnSe sample of 212-µm thickness at a wavelength of 470 nm are shown and discussed. The phenomenological theories have been extended to include the carrier recombination mechanism in order to simulate experimental results. By fitting the theories to the experiment, the nonlinear refractive index cross section (i.e., the nonlinear refractive index change per pair of photogenerated carriers) and the carrier recombination time were obtained.