Fundamental-frequency pulse compression through cascaded second-order processes in a type II phase-matched second-harmonic generator

We show that cascading of the second-order processes under large group-velocity mismatch can lead to the efficient compression of pulses at fundamental frequency in the type II phase-matched second-harmonic-generation process. We demonstrate that any of three interacting pulses can be compressed if thee proper ratio of intensities of the o- and e-polarized pump pulses is chosen on input. We experimentally achieved compression of o-polarized pulses from 1.3 ps down to 280 fs with energy conversion close to 50%. when a conventional second-harmonic compressor with unbalanced intensities of the pump pulses was used. (C) 1996 Optical Society of America