We report on the experimental observation of nonlinear mixing between Raman-shifting solitons and residual pump radiation in supercontinuum generation in the long-pulse regime. This resonant coherent process results in the generation of strong and isolated spectral components on the long-wavelength normal dispersion regime of a fiber with two zero-dispersion wavelengths. Our observations are in excellent agreement with numerical simulations and calculated phase-matching conditions.
© 2011 Optical Society of America