Parametric excitation of continuously tunable visible picosecond pulses

An experimental investigation was made of parametric generation of ultrashort light pulses in KDP and ADP crystals pumped with the third and fourth harmonics of single picosecond pulses emitted from a YAG:Nd³⁺ laser. The frequency width of the parametric superluminescence ranged from 10 to 5300 cm^–1 depending on the phase conditions in the three-frequency interaction and the focusing parameters of the pump radiation. The efficiency of conversion of the pump radiation reached 10–15%. The results demonstrated potential usefulness of the parametric superluminescence continuum in picosecond spectroscopy.