The optical laser – known internally as the Pump-Probe (PP) laser – is a non-collinear parametric amplifier (NOPA) developed by the Laser Group at European XFEL to match the pulse structure of the FEL. It delivers bursts of pulses at 10 Hz with variable intra-burst repetition rate and is synchronized with the FEL. Details of the laser can be found in the following publications:
M. Pergament et al. Optics Express 22 (18) 22202 (2014)
M. Pergament et al. Optics Express 24 (26), 29349 (2016)
The laser has two fundamental operating wavelengths – 800 nm and 1030 nm. The 800 nm beam can be configured to 15 fs or 50 fs. The 1030 nm beam is 850 fs long and will be compressed in a multi-pass Herriot cell (HMPC) to either 40 fs or 150 fs (this is currently being developed). The key difference between them is the pulse energy at a given repetition rate. At 800nm, 2mJ pulses are available only at 113 kHz, whereas at 1030 nm, the same pulse energy is available at 1.1 MHz. Second- and third harmonics of these wavelengths are available for 800 nm at 50 fs and 1030nm at 40 fs. The table below summarizes the parameters of both the 800nm and 1030nm lasers available for experiments at different intra-burst repetition rates.