Short-wavelength stimulated Raman scattering in a silica fiberpumped by an XeBr excimer laser

A UV-grade silica optical fiber was pumped by a 281.8-nm XeBr excimer laser. The first Stokes spectrum was observed at 285 nm. The spectral width was one-half of that of the spontaneous Raman spectrum. A numerical analysis of stimulated Raman scattering which includes two-photon absorption loss is presented. The Raman gain coefficient, determined by an analysis of the nonlinearity observed in the Stokes output, was 1.8×10^-5 cm/MW. The analysis also indicates that two-photon absorption is a more important loss factor than linear attenuation. The short wavelength limit of net amplification by stimulated Raman scattering is estimated to be 272 nm