High average power Ti:sapphire drive laser
Artemis provides ultrafast, synchronised laser pulses which can be configured flexibly either to generate XUV or as pump and probe pulses spanning the UV to far infrared. The core of the facility is a 30 fs, 1 kHz Ti:Sapphire CPA system operating at 780 nm (RedDragon from KMLabs). A recent upgrade to the second amplifier stage has increased the maximum output power to >13 W. The laser has two grating compressors, allowing us to optimise pulse durations of pump and probe beams independently. We run the laser continuously, 24 hours a day, for periods of up to three weeks at a time, to enable us to carry out long data acquisition series and to maximise the science output of the facility.
Tuneable pulses spanning the spectral range from 235 nm to 15 microns are provided by an optical parametric amplifier (HE-Topas from Light Conversion). This is pumped with up to 8 mJ of the output from the laser system. At 1300 nm, we have achieved pulse energies of up to 1 mJ with a 40 fs pulse duration, enabling focused intensities exceeding 1014 Wcm-2 .
Pulse energies in excess of 100 microJ at 250 nm and 2 microJ at 20 microns can be obtained. The shot-to-shot energy stability of the output is ~3% rms.
Part of the output energy of the laser can be split and spectrally broadened in a gas-filled hollow fibre and then recompressed. By focusing 1-2 mJ at 800 nm into the fibre and recompressing with chirped mirrors, we have shown that we can produce pulses as short as 7 fs with energies of 0.5 mJ.
We can also offer few-cycle pulses in the infrared, by sending the idler from the Topas at 1700 nm into a fibre and recompressing with glass wedges. This produces 12 fs pulses with a spectrum spanning 1200-2200 nm, with 0.4 mJ/pulse. This few-cycle idler capability has been developed in partnership with the Laser Consortium (link opens in a new window) at Imperial College.