High intensity, high contrast OPCPA/Yb:YAG hybrid laser system

Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Nakai, Yoshiki*; Daido, Hiroyuki; Bolton, P.; Sugiyama, Akira; Kondo, Kiminori; Kawanishi, Shunichi; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; Kan, Hirofumi*

At our Institute we are developing a compact ion accelerator for cancer therapy using a laser-driven plasma point source of ions. The laser system was consisted of an oscillator, offner stretcher, optical parametric amplifier (OPCPA), LD pumped Yb:YAG amplifier, and compressor. In OPCPA the stretched laser pulse after the pulse stretcher was amplified to 5 mJ with only a 0.2 mJ input. After amplification in the OPCPA laser pulse was further amplified by an Yb:YAG (5 at%) thin disk module which was pumped by the Q-CW LD. The maximum output energy was about 120 mJ in a multi-pass scheme (20 pass) at 10 Hz. The compressed pulse duration is about 300 fs, and the contrast level before the main pulse is measured as 10 at -150 ps. We have developed that new high intensity, high contrast femtosecond OPCPA/LD-pumped Yb:YAG hybrid laser system. This novel system might represent the driver in integrated, laser-driven ion accelerator systems.