2ND-HARMONIC GENERATION UNDER PHASE-VELOCITY AND GROUP-VELOCITY MISMATCH - INFLUENCE OF CASCADING SELF-PHASE AND CROSS-PHASE MODULATION

Temporal and spectral characteristics of pulses resulting from second- harmonic generation of 120-fs amplified Ti:sapphire laser pulses up to 0.1 mJ at a wavelength of 815 nm in type I KDP crystal were experimen tally and theoretically analyzed. Widely different behaviors were obse rved, according to the sign of the phase mismatch. Comparison between the theoretical simulation and experimental data demonstrates that the competition between third- and second-order nonlinear phenomena stron gly modifies the structure of the pulses generated. (C) 1997 Optical S ociety of America.