Brillouin scattering spectra for oxide and halide glasses: intrinsic Brillouin linewidths and stimulated Brillouin gain

Abstract

Brillouin scattering measurements on various multicomponent halide and oxide glass compositions were done as a function of composition, lattice temperature, and configurational temperature. The intrinsic Brillouin linewidth measurements, Brillouin intensities, and Brillouin frequency shifts allowed the calculation of phonon attenuations, the Pockels elastooptic coefficients, and the stimulated Brillouin scattering gain coefficients. From the parameters obtained in the above measurements we are able to calculate the threshold energy for the onset of stimulated Brillouin scattering in halide and oxide glasses. Results show that the threshold power for stimulated Brillouin scattering is larger in some of the halide glass compositions than some of the silica-based glasses. This finding has important ramifications as a selection criteria for halide-based glasses vs oxide based glasses in their use as possible single-mode waveguide materials. The phonon attenuation values of some of the halide glasses, as measured from the linewidth data, had magnitudes that correspond more to a liquid than a solid. These anomalous phonon attenuation findings are discussed in light of existing theories.