Pump-probe laser development for the European X-Ray Free-Electron Laser Facility

The successful implementation of superconducting LINAC technology at the European XFEL will boost the time averaged X-RAY power density substantially above current values. In fact, the XFEL will operate at repetition rates of up to 4.5MHz. However, this high pulse rate occurs only during 600 mu s long bursts of 10Hz repetition rate, rendering up to 27000 pulses per second. Matching this peculiar burst mode operation is a requirement also for the pump-probe femtosecond laser used in experiments. There is currently no commercially available femtosecond laser technology offering this kind of output at close to mJ-level energies per pulse and sub-20fs pulse width. We will outline the scheme of the pump-probe laser currently under development at the European XFEL. The laser design is based on a non-collinear optical parametric amplifier (NOPA) which will be pumped by sub-picosecond pulses from a high power, frequency-doubled Yb:YAG slab amplifier, delivering up to 20kW of fundamental average power during a burst. The design aims at highest possible flexibility regarding intra-burst rep-rates and pulse energies. Also, the use of uncompressed as well as compressed NOPA pump pulses at fundamental wavelength will enhance the flexibility in experiments.