Laser Processes and Optical Nonlinearities in ZnSe-Based Heterostructures

Abstract

Supported by the recent progress in epitaxial growth and doping of II-VI semiconductors, ZnSe-based heterostructures have become highly promising material systems for a commercial fabrication of laser diodes or other optoelectronic devices operating in the blue spectral range. Our interest in this field is concerning the identification of the microscopic origins of the optical gain and other nonlinear optical effects in these heterostructures with a focus on the role of excitons. Information about the underlying recombination process is drawn from a combination of different spectroscopic techniques. Gain spectra are determined from the variable stripe-length method and by pump and probe measurements, which simultaneously provide the nonlinear absorption changes in the spectral regime of the excitonic resonances. A lineshape analysis on the experimental data of the gain and of the luminescence is then performed according to theoretical models for the relevant processes. Furthermore, the redshifts of the stimulated emission at threshold and of the excitonic absorption lines with increasing lattice temperature are compared.