Noncollinear optical parametric amplifiers with output parameters improved by the application of a white light continuum generated in CaF2

We report the drastic improvement of output parameters of femtosecond noncollinear optical parametric amplifiers by applying supercontinuum seed pulses generated in CaF2 instead of sapphire and imaging via all reflective optics. Features of the setup are broad amplification bandwidths up to 310 THz (470-910 nm), an almost Gaussian beam profile, a divergence with M-2 factor of less than 1.4, pulse to pulse energy fluctuations of less than 2.5% and compressibility of the pulses down to 16 fs. The high intensity of the supercontinuum seed pulse (80 nJ) yields a quantum efficiency for the conversion of pump to signal of more than 30%. Even for short wavelengths e.g. at 470 nm pulse energies above 30 muJ were obtained for 110 muJ of 400 nm pump light. (C) 2001 Elsevier Science B.V. All rights reserved.