2ND-HARMONIC GENERATION OF FEMTOSECOND HIGH-INTENSITY TI-SAPPHIRE LASER-PULSES

The second-harmonic generation (SHG) of ultrashort Ti:sapphire laser p ulses in potassium dihydrogen phosphate crystal in type-I phase-matchi ng geometry has been investigated theoretically, including the effects of cubic nonlinearity. It is found that the phase mismatch due to the broad bandwidth associated with the short pulse width limits the maxi mum conversion efficiency to less than 60%, and the temporal shape of the converted pulse has an intensity modulation at an incident intensi ty of 100 GW/cm(2) for a 100 fs pulse. In order to increase the energy conversion efficiency and improve the temporal pulse shape, a new SHG geometry using two antiparallel tilted crystals is discussed. (C) 199 8 American Institute of Physics.