Highly efficient conversion of picosecond Nd laser pulses with the use of group-velocity-mismatched frequency...

We report an increase in the conversion efficiency from approximately 40% to approximately 75% for type II frequency doubling of 1.053-microm, 1.6-ps-duration pulses in KDP when a delay of approximately 1.45 +/- 0.1 ps between the extraordinary and ordinary pulses is introduced at the input to the doubling crystal. The delay compensates for the effect of group-velocity dispersion in the crystal with the result that the effective interaction length in the crystal is approximately doubled.