10 J operation of a conductive-cooled Yb:YAG active-mirror amplifier and prospects for 100 Hz operation
Jumpei Ogino, Shigeki Tokita, Shotaro Kitajima, Hidetsugu Yoshida, Zhaoyang Li, Shinji Motokoshi, N. Morio, Koji Tsubakimoto, Kana Fujioka, Ryosuke Kodama, Junji Kawanaka
Abstract
We report, to the best of our knowledge, the highest power conductive-cooled active-mirror amplifier (CcAMA) using Yb:YAG with a pulse energy of 10 J. By using four liquid-nitrogen circulating cooled laser heads, we achieved a repetition rate, pulse energy, and average power of 33.3 Hz, 9.3 J, and 310 W, respectively. The problem of wavefront distortion, which is difficult to solve with a large-aperture active-mirror laser, is suppressed by using reinforcing materials with the same thermal expansion coefficient. We have confirmed that the wavefront distortion is small ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0.15</mml:mn> </mml:mrow> <mml:mi>λ</mml:mi> </mml:math> P-V per head) at 100 Hz operation, which paves the way for 100 Hz operation with the CcAMA concept.