Raman-induced pulse self-frequency shift in crystalline ultrashort pulsed mode-locked lasers

Summary form only given. The ultrashort pulse spectra, offset to the red from the maximum of the gain spectrum, were published in several papers on Ti:sapphire as well as Cr:LiSAF and Cr:YAG mode-locked lasers. The red shift was either explained by dispersion effects or left without discussion. Recently, we reported an infrared pulse self-frequency shift in Cr:LiSAF and Cr:LiSGaF lasers, suggesting an alternative mechanism, based on induced Raman scattering as a first-order nonlinear perturbation, directly influencing the spectral position of the pulse. In this paper we present the results of experimental investigation of this phenomenon (mode-locking experiments and Raman gain measurements) in crystals, commonly used in mode-locked lasers (e.g., Ti:sapphire, Cr:LiSGaF, Cr:LiSAF, Cr:YAG, etc.) and compare them with the theory.