High power Nd:YAG ceramic lasers: passive Q-switching and frequency doubling

A high power passive Q-switched laser and a continuous-wave (CW) green laser both with a neodymium-doped yttrium aluminum garnet (Nd:YAG) ceramic as the laser material have been demonstrated. Two Cr4+:YAG crystals with 73.9% and 79.6% initial transmission at 1064 nm have been used as saturable absorbers. In Q-switched regime the laser generated up to 209 μJ, 4.5 ns pulses, which corresponds to a peak power of 46.8 kW. In CW regime at 1064 nm the laser generated 11.3 W of output power at a pump power of 21.6 W, corresponding to an optical-optical conversion efficiency of 52.3%. By using a type-II cut KTP crystal, the CW frequency-doubled operation of Nd:YAG ceramic was achieved. The maximum output power of 1.86 W at 532 nm has been obtained. The one-dimensional intensity distribution of the green beam cross-section was observed to be Gaussian. When the output power was 1 W, the M2 factor was measured to be 1.7.