High power fiber-coupled acousto-optically Q-switched 532 nm laser with a side-pumped Nd:YAG laser module

We demonstrated a high power laser at 532 nm by frequency-doubling of an acousto-optically Q-switched and side-pumped Nd:YAG laser at 1064 nm using a compact linear cavity. The average output power of the pulsed fundamental laser at 1064 nm was as high as 299 W. The laser employed two acousto-optic Q-switches placed orthogonally with each other to improve the hold-off capacity. Through intracavity frequency doubling with a type II non-critically phase-matched LBO crystal, a 165 W average power of the frequency-doubled output at 532 nm was generated with a repetition rate of 20 kHz and pulse width of 160 ns, which corresponds to a pulse energy of 8.25 mJ and a peak power of 51.6 kW, respectively. The output power of the green laser was very stable and the stability at various output powers was measured. The RMS instability was ±1.4% when the output power of 532 nm was 135 W. After coupling the 165 W output power at 532 nm into an 800 μm fiber, the final output from the optical fiber was 149 W with a coupling efficiency of 90.3%.