Abstract

Quasi-elastic light scattering spectroscopy has long been used to probe the dynamics of thermal diffusion, sound propagation and structural relaxation in condensed matter. Ordinarily the region around zero frequency shift in such spectra is dominated by the Rayleigh line, due to temperature/entropy fluctuations. Some materials, however, show an additional central peak attributed to structural or molecular relaxation processes¹. In a heterodyne detected back scattering experiment in cooled fused silica optical fiber, we have discovered a new light scattering component with a power law spectrum and an unusual temperature dependence. Previous reported measurements of light scattering in glass have had neither the sensitivity nor the resolution near 0 Hz to see either Rayleigh scattering or this new narrow linewidth scattering.

© 1988 Optical Society of America