Wavelength dependence of brillouin-gain spectra for single-mode optical fibres

Brillouin-gain profiles are measured for fused-silica core and GeO₂-doped core fibres at wavelengths of 1286 nm and 1550 nm. The intrinsic Brillouin linewidth is found to vary as the square of optical frequency, as predicted for bulk fused-silica. However, the experimentally evaluated Brillouin line-widths at both wavelengths are broader by a factor of 2.5 than those predicted for the bulk glass.