Brillouin scattering spectrum partially germ in photonic crystal fiber with a partially germanium-doped core

The Brillouin scattering spectrum in a photonic crystal fiber (PCF) with a partially Ge-doped core is measured with a pump-probe technique at a wavelength of 1320 nm. One main peak and four subpeaks are observed. The main peak has a Lorentzian shape with the bandwidth Deltanu(B) = 66 MHz. Its intensity is six times higher than that from a standard single-mode fiber measured under the same conditions, which is consistent with the ratio of (1/A(eff)(PCF) )/(1/A(eff)(SMF)), where A,(ff) is the effective area of the fibers. The temperature coefficient for the main peak is 0.96 MHz/degreesC. We believe that the subpeaks are caused by an interaction between light-wave and guided modes of longitudinal acoustic waves in the graded-Ge-doped region, the silica region, and the microstructured cladding. An analysis of the guiding and antiguiding properties of the PCF for acoustic waves is presented. (C) 2003 Optical Society of America.