Laser

Dr. Piotr Wiewior - Mgr. Laser Team
Yuriy Stepanenko - Post Doc
Oleksande Chayl - Developmental Technician IV
Joseph Vesco - Student

The "Leopard" laser is a powerful and versatile laser system capable of delivering 10-20J of laser energy in 300 fs long pulses at 1057 nm. The laser attains an intensity of 10¹⁸ W/cm² and after implementation of the adaptive optics system (planned for 2008) will reach 10¹⁹ W/cm².

The "Leopard" laser operates in the ultra-high intensity regime using the technique of Chirped Pulse Amplification (CPA). In CPA systems, a low intensity pulse is stretched in time from approx. 200 fs to approx. 1 ns long pulse. The long pulse is then amplified, overcoming nonlinear effects in the amplifiers chain. After final amplification stage the pulse is being recompressed in vacuum optical compressor (Falcon) and focused onto a target

The front-end comprises a commercial fs oscillator (SpectraPhysics Tsunami), pumped by cw 10 W diode-pumped Nd:YVO₃ laser (SpectraPhysics Millenia Pro Xs), a Offner-type chirped pulse stretcher unit and a commercial linear regenerative amplifier (Coherent). The regenerative amplifier is pumped by a frequency-doubled Nd:YLF laser operating at 500 Hz repetition rate (Evolution-30, Coherent). The system provides frequency-chirped, stretched pulses with nearly 10 nm bandwidth and energy of 1 mJ for the injection into the flash lamp-pumped amplifiers section. The contrast ratio was improved to the level of 10^-6 by adding an ultra fast Pockels cell (UPC, Leysop Ltd) at the output of the regenerative amplifier. The complete Offner stretcher unit was built in house. It converts 150 fs pulses from the fs oscillator to 1.2 ns long chirped pulses, which are then amplified at irradiance well below the self-focusing threshold.

Falcon - Optical vacuum compressor It uses two parallel gold gratings with a groove density of 1740/mm and the roof mirror. The laser beam enters the compressor chamber and is diffracted by a first grating onto a second one, which re-collimates it and directs to the roof mirror. The roof mirror reflects the downward and then back to the second grating, which diffracts the beam back to the first one. The beam is then reflected by a number of turning mirrors and exists the compressor chamber. The leak from the last turning mirror is used for the diagnostics purposes.

Phoenix - Laser Target Chamber After passing the compressor, the laser beam is directed toward the Phoenix target chamber for stand-alone laser experimenst or toward the Zebra target chamber for coupled Leopard-Zebra experiments. A broad range of experimental configuration is available in both locations, including plasma diagnostics.