Abstract
Micro-MOPA, which is a master oscillator power amplifier system with a microchip-based sub-ns laser
and a beam cleaning gain aperture, can generate extremely high brightness of 18 PW/sr･cm2 with 200-
mJ pulses1). However, the current repetition rate of the Nd:YAG-rod amplifier in our Micro-MOPA was
limited to 10 Hz due to its thermal problems under high power operation. In this work, we achieved 100-
Hz operation in a PW/sr･cm2-class Micro-MOPA by optimizing the optics from the evaluation of the
thermal lens effect in a highly excited Nd:YAG-rod of Micro-MOPA.
