Multi-sideband generation in a femtosecond Cr4+:YAG laser

We describe the behavior of multi-sidebands in a self-mode-locked femtosecond Cr4+:YAG laser operating near 1.54 mu m. Stokes and anti-Stokes sideband components are extended over 20 THz around the center frequency. An interesting feature here is that when the spectral width of the mode-locked pulse is increased, the specific Stokes sideband near 1.65 mu m (a shift of 13.5 THz) is strongly enhanced due to an induced-Raman process in the laser rod. The measured frequency shifts for all sidebands are well explained by four-wave-mixing processes in the laser rod, accompanied by the resonance effect of the soliton and dispersive wave, both of which are affected mainly by cavity dispersions.