High-peak-power, high-contrast OPCPA/Ti:sapphire laser system

Kiriyama, Hiromitsu; Mori, Michiaki; Daito, Izuru; Kotaki, Hideyuki; Kanazawa, Shuhei; Kondo, Shuji; Nakai, Yoshiki; Shimomura, Takuya*; Tanoue, Manabu*; Akutsu, Atsushi; Okada, Hajime; Motomura, Tomohiro*; Daido, Hiroyuki; Bulanov, S. V.; Kimura, Toyoaki

We report a high-peak-power, high-contrast laser system, which combines both conventional Ti:sapphire chirped-pulse amplification (CPA) and optical parametric chirped-pulse amplification (OPCPA) techniques for use in experiments where relativistic effects dominate the physics. We have achieved an amplified energy of 2.9 J and an ultrashort recompressed amplified pulse duration of 19fs, corresponding to the peak power of 80 TW, at a 10 Hz repetition rate. With the use of OPCPA, the pre-pulse contrast is enhanced to better than 7 10 in a few picoseconds before the main pulse, which corresponds to an improvement of three to four orders in magnitude compared with conventional systems. By cooling the crystal in the final Ti:sapphire power amplifier down to 77 K, the thermal focal length of about 4 km is obtained when pumped with the maximum pumping condition and has almost no effect on thermal lensing.