4TH HARMONIC-GENERATION AND PULSE-COMPRESSION OF A PICOSECOND LASER-PULSE

This paper describes harmonic generation and pulse compression of a pi cosecond laser pulse. By applying a time delay between the extraordina ry and ordinary waves of the fundamental pulses, the group velocity mi smatch and the nonlinear phase shift can be compensated by each other, resulting in pulse-width reduction at the fourth harmonic wavelength. It is shown that the reduction from 1 ps fundamental pulse to 0.25 ps fourth harmonic pulse with 45% energy conversion efficiency can be ac hieved at the incident intensity of 50 GW/cm(2).