Enhanced supercontinuum generation in the normal dispersion pumping regime by seeded dispersive wave emission and stimulated Raman scattering

We numerically investigate the active enhancement of the seeded-supercontinuum (SC) generation pumped in the normal dispersion regime. When the minute seed (100,000 weaker than the pump peak power) spectrally coincides with the Raman gain peak of the pump, the SC bandwidth can be drastically enhanced to more than one octave, even when the pump is far away from zero dispersion wavelength (ZDW) (similar to 100 nm) in the normal dispersion regime. In such a relatively "deep" normal dispersion pumping scenario, a phase-matched parametric process plays a negligible role in spectral broadening. Instead, we observe that initial spectral broadening is not only greatly accelerated by the seed through the cascaded stimulated Raman scattering (SRS). More importantly, the seed also promotes shock-wave-induced wave breaking, which induces dispersive wave emission in the anomalous dispersion regime. This effect together with the seeded higher-order SRS cascades efficiently trigger the subsequent soliton fission - resulting in an ultrabroadband SC. We anticipate that this new seeding mechanism could open up opportunities to expand the scope of active seeding mechanism for enhancing SC generation to the normal dispersion regime. (C) 2014 Elsevier B.V. All rights reserved