Diode-pumped solid-state laser produces 315 W of pulsed green output
A diode-pumped Nd:YAG laser at Lawrence Livermore National Laboratory (Livermore, CA) produced an average power of 315 W at 532 nm. Designed with a side-pumped Z-shaped resonator, the intracavity frequency-doubled device produced two green-output beams, according to researcher Jim Chang, who presented the results at CLEO `98 (San Francisco, CA). The dual-output scheme was chosen to minimize power loading in the frequency-doubling crystal and in the optical fibers used for light delivery. A two-mirror telescope in the resonator reduced the laser spot size in the doubling crystal.
Compound parabolic concentrators efficiently coupled the CW diode-laser pum¥radiation into a closely coupled pum¥chamber enclosing a 0.6% neodymium-doped YAG rod, Chang said. Acousto-optic Q-switches on each end of the rod provided efficient cavity hold-off during pulsed operation, and the ratio of pulsed-to-CW output was about 91% at a 13-kH¥pulse-repetition frequency (PRF). The 315-W output was achieved at a 17-kH¥PRF with a hydrothermally grown potassium titanyl phosphate (KTP) doubling crystal and at a 30-A diode current. The optimal electrical-to-green conversion efficiency was 8.3%, and frequency- conversion efficiency was 82% at a diode current of 29 A, Chang said.