EFFECTS OF GROUP-VELOCITY DISPERSION ON THE EVOLUTION OF OPTICAL PULSES IN A MODE-LOCKED LASER USING A SINGLE SHG CRYSTAL

The effects of group-velocity dispersion in an SHG crystal on the evol ution of optical pulses in a mode-locked laser by a nonlinear mirror a re analysed. The pulse duration is determined by the balance between p ulse stretching due to the group-velocity dispersion of the SHG crysta l and pulse shortening due to the intensity-dependent reflection coeff icient of the nonlinear mirror. Theoretical calculation shows that the final pulse duration is mainly confined by the group-velocity mismatc h of the fundamental and the second harmonic in the nonlinear crystal.