Soliton transients and supercontinuum generation in high-Raman-gain materials

Modification of the Raman response of a nonlinear-optical material can dramatically change the spectral and temporal evolution of ultrashort pulses, leading to new interesting and practically significant regimes of short-pulse dynamics. We show that, in fibers with a high Raman gain, solitonic spikes can arise only as transient features in the fast dynamics of ultrashort field waveforms. Enhanced Raman scattering induces a fast frequency downshift of these transients, preventing the formation of temporally and spectrally isolated solitons and giving rise to new highly efficient regimes of supercontinuum generation. (c) 2006 Optical Society of America