The ATF is one of the only two facilities worldwide operating picosecond, terawatt-class CO2 lasers. Our laser system consists of a picoseconds pulse-injector based on fast optical switching from the output of a conventional CO2 laser oscillator, and a chain of high-pressure laser amplifiers. It starts with a wavelength converter wherein a near-IR picosecond solid-state laser with l»1 μm produces a mid-IR 10-μm pulse. This process employs two methods; semiconductor optical switching, and the Kerr effect. First, we combine the outputs from a multi-nanosecond CO2 laser oscillator with a picosecond Nd:YAG laser on a germanium Brewster-plate to produce an ~200 ps, 10μm pulse by semiconductor optical switching. Co-propagating this pulse with a Nd:YAG’s 2nd harmonic in a Kerr cell filled with an optically active CS2 fluid, we slice out a 5 ps, 10μm pulse at the ~0.1 MW peak power-level.
Immediately after a low-power, 10 μm, seed pulse is produced, it is amplified in a chain of high pressure (~10 atm.) CO2 laser-amplifiers. At the first stage, the pulse is seeded into an isotope-filled CO2 regenerative amplifier where it is trapped for 10-12 round trips and then released on reaching the ~1 GW level. A final high-pressure, large-aperture (10 cm) amplifier boosts the laser pulse to 1 TW for use in the experiments discussed above. The figure above is a principle diagram of the ATF laser system. For more technical details, refer to Optics Express, Vol. 19, Issue 8, pp. 7717-7725 (2011) or contact ATF Director Igor Pogorelsky.
A major CO2 laser upgrade to the multi-terawatt ultra-fast regime is being implemented.