Luminescence and lasing of ZnSe single crystals subjected to one- and two-photon excitation

A study was made of the luminescence and of the amplification, and generation of coherent radiation in ZnSe single crystals subjected to two-photon excitation by ruby laser radiation. Lasing appeared at pump power densities 10–20 MW/cm², depending on the resonator length, and the emitted photon's energy was in the range 2.73–2.76 eV. The divergence of the output radiation was approximately 10°. An investigation of the luminescence spectra obtained under one-photon excitation conditions together with the gain spectra indicated that the main mechanisms responsible for lasing were exciton–phonon and exciton–exciton interactions.