  A number of factors that influence spectral position of the femtosecond pulse
in a Kerr-lens modelocked Cr:LiSGaF laser have been identified: high-order
dispersion, gain saturation, reabsorption from the ground state, and stimulated
Raman scattering. Using the one-dimensional numerical model for the simulation
of the laser cavity, the relative contributions of different factors have been
compared. The Raman effect provides the largest self-frequency shift from the
gain peak (up to 60 nm), followed by the gain saturation (25 nm), while the
high-order dispersion contribution is insignificant (5 nm). Comparison with the
experimental data confirm that the stimulated Raman scattering is a main cause
of the ultrashort pulse self-frequency shift observed in Cr:LiSGaF and Cr:LiSAF
lasers
