Abstract

Both high pulse energy and repeatable operation are simultaneously desired for high-power lasers in the next generation. These lasers are expected to be useful tools for various kinds of advanced fields such like inertial fusion energy, neutron sources, debris remove, PET and so on. The target of 1-kJ, 100Hz in pico seconds is set for novel laser technology developments. The most significant problem in the developments is laser materials which require high thermal strength, material size scalability and suitable emission cross section (saturation fluence). Cryogenic Yb:YAG ceramic has shown good performances via our previous basic experiments.[1,2] In addition, a total-reflection active-mirror (TRAM) amplifier has been proposed for high efficiency, compactness and high optical damage threshold. So-called active-mirror amplifiers show high efficiency due to a good spatial overlap between a pump and a laser beam. The optical damage threshold reduced due to interference on the input/output surface is, however, significant for pulse duration. The TRAM recovers it. A few temperature rise in cw operation showed considerably high thermal strength.[3] In pulse operation as following, a regenerative amplifier is developed and an additional joule-class amplifier system at 100 Hz is under construction.

© 2011 Optical Society of America