EFFICIENT 3RD-HARMONIC GENERATION OF A PICOSECOND LASER-PULSE WITH TIME-DELAY

A new configuration based on the polarization-mismatching scheme with time delay for efficient frequency tripling conversion is proposed in this paper, The calculated results showed that the requirement for the efficient frequency tripling conversion of a l-ps laser pulse is not only the optimization of peak intensity of the second-harmonic pulse, but also the optimization of the pulse duration ratio and temporal dif ference between the o-polarization second-harmonic pulse and the e-pol arization first-harmonic pulse due to group-velocity mismatch among th e interacting pulses, With the proposed scheme the group velocity mism atch can be compensated, Overall energy conversion efficiency increase s from 55% to 75% under the optimized conditions at the intensity of 6 GW/cm(2), The temporal shape of the third-harmonic pulse with 1 ps pu lse duration has no subpulses. The optimization of the efficient frequ ency tripling conversion for intensities of over 75 GW/cm(2) is also d escribed, The results showed that the maximum tripling energy conversi on efficiency is close to 80% with the optimized doubler and tripler.