Group-velocity self-matching of femtosecond pulses in noncollinear parametric generation

Abstract
We show that the parametric superfluorescence generated by a 200-fs pulse at 0.6 μm in a β-barium borate crystal occurs in directions, and at wavelengths, that minimize the group-velocity mismatch between pump and generated pulses. Favorable conditions for generation of tunable femtosecond pulses are found in noncollinear phase matching, a geometry of interaction which is worth exploiting in parametric devices.