G.M.H. Knippels, A.F.G. van der Meer
FOM-Institute for Plasma Physics, P.O. Box 1207, 3430 BE, Nieuwgein, The Netherlands
We present a new technique to increase the optical pulse energy of an FEL from a few microjoules up to the millijoule level. The amplification process is based on parametric interaction in a AgGaS2 crystal with a powerful picosecond Nd:YAG pulse. In this amplification process, the tunable FEL output serves as a seed for the idler wave, which is amplified by the 1.064 micron pump (0.1 Joule, 70 ps) with, as a by-product, the signal beam (1.19-1.65 micron). The useful amplification range is from 3-12 micron, limited by the transparancy of the parametric crystal. The energy extraction from the much longer Nd:YAG pulse can be greatly enhanced if the well-known chirped-pulse amplification scheme is used. With signals in nonlinear spectroscopy scaling at least quadratically with power, the proposed boost in peak power will be extremely important for research in the field of ultra-fast dynamics of disordered and complex systems, benefiting almost all (international) users coming to the FELIX facility. Both simulations as well as experimental results will be presented.
