Two-photon polarization laser spectroscopy of the electronic structure of laser active defects in cubic crystals

Summary form only given. The identification of "hidden" energy levels of laser active defects, i.e. levels not participating in one-photon transitions, is important since these levels determine the nonlinear properties of a laser medium as well as the dynamics of the relaxation processes following electronic excitation. We investigated, for the first time, the polarized fluorescence behavior of optically isotropic cubic crystals with laser-active defects under two-photon excitation.