Efficient amplification of a femtosecond Ti:sapphire laser with a ring regenerative amplifier.

A high-stability and high-efficiency ring Ti:sapphire regenerative amplifier is demonstrated based on a double-gating pulse picker at a repetition rate of 1 kHz. Pulse energy up to 5.7 mJ is obtained using a pump energy of 20.0 mJ at 527 nm, corresponding to a relatively high slope efficiency of 30.3%. After a grating compressor, the laser pulse is compressed to 37.2 fs with an energy of 4.1 mJ. The beam quality factors M(2) are 1.4 and 1.3 in tangential and sagittal directions, respectively. The measured root mean square energy stability is better than 0.31% over an 11 h period.