A sub-10 fs noncollinear optical parametric chirped pulse amplifier pumped at 20 kHz pulse repetition rate

We demonstrate a two-stage three-pass non-collinear optical parametric chirped-pulse amplifier delivering 125 μJ pulse energy at 20 kHz repetition rate, corresponding to an average power of 2.5W. The system is pumped by a 20 kHz Nd:YVO4 regenerative amplifier system. A grism-pair stretcher stretches the 6 fs seed pulses to more than 100 ps from 650nm to 1000 nm. The amplified signal pulses are compressed with SF57 and fused silica glass blocks. Using an acousto-optical programmable dispersive filter to compensate the residual higher-order dispersion pulses of 9.6 fs duration are obtained which corresponds to a peak power of 13GW. We estimate the level of parametric superfluorescence with the spectral hole technique.