A number of factors that influence spectral position of ultrashort pulses in mode-locked lasers 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, we analyze the relative contributions of different factors to the spectral position of the mode-locked pulses using the example of the Cr:LiSGaF laser. In this case the Raman effect provides the largest self-frequency shift from the gain peak (up to 60 nm), followed by the gain saturation (∼25 nm), whereas the high-order dispersion contribution is insignificant (∼5 nm). The results of the simulation are in good agreement with experimental data, confirming that stimulated Raman scattering is the dominant mechanism that causes the pulse self-frequency shift.
© 2001 Optical Society of America
Vladimir L. Kalashnikov, Evgeni Sorokin, and Irina T. Sorokina, "Mechanisms of spectral shift in ultrashort-pulse laser oscillators," J. Opt. Soc. Am. B 18, 1732-1741 (2001)