Christopher Arrell, Andreas Mann, Frank van Mourik, Fabrizio Carbone, Majed Chergui
A 15 W cryogenically cooled regenerative amplifier drives the high harmonic beamline. The output of the laser can be tuned from 3 – 15kHz providing 1 – 3 mJ of energy per pulse, while maintaining 0.3 -0.5% RMS shot-to-shot noise. The laser centred at 785 nm, produces 45 fs FWHM pulses.
The output spectrum of the laser can be spectrally broadened to over an octave using a hollow fibre pulse compressor. The differentially pumped ~ 1 m fused silica waveguide maintains a pressure gradient of typically argon of neon. The laser output is coupled into the fibre, and due to the high intensity of the laser self phase modulation and spectral broadening occurs.
The broad spectrum allows the pulse to be further compressed with chirped mirrors to ~ 8 fs. The efficiency of the compression is 50% producing a 7 W average power 8 fs source tunable from 3 -15 kHz, currently unique in the world.
The laser system is currently used for: