2ND-HARMONIC GENERATION FROM INTENSE, 100-FS TI-SAPPHIRE LASER-PULSESIN POTASSIUM DIHYDROGEN PHOSPHATE, CESIUM LITHIUM BORATE AND BETA-BARIUM METABORATE

Second-harmonic generation of femtosecond, intense Ti:sapphire laser p ulses is described in three I-mm-thick nonlinear crystals of KDP (KH2P O4), CLBO (CsLiB6O10) and BBO (beta-BaB2O4) in type I phase-matching g eometry. The phase-matching bandwidth is insufficient for BBO. Spectra l modulation due to cubic nonlinearity becomes significant at 200 GW/c m(2) for KDP and 30 GW/cm(2) for CsLiB6O10. The energy conversion effi ciencies obtained at incident intensities where the spectral modulatio ns scarcely change the temporal profile of the second harmonic were 20 % for both the crystals. Numerical calculations including the effects of cubic nonlinearity and group-velocity mismatch explained the experi mental results. It is found that a 1-mm KDP crystal gives the most eff icient conversion for high-power, 100 fs pulses.