Abstract

Generation of tunable sub-20-fs visible pulses is demonstrated by optical parametric amplification of a white light continuum in a 2 mm thick BBQ crystal. The necessary broad amplification bandwidth is ensured by noncollinear type I phase matching. The proper angle between the seed light and the second harmonic of the Ti:sapphire pump light leads to an effective matching of the signal and idler group velocities. Above the degeneracy point this is not possible in the type I arrangement but it is shown that type II phase matching can be used instead to produce similarly short pulses in the NIR.

© 1999 Optical Society of America