82 W Continuous-Wave Green Beam Generation by Intracavity Frequency Doubling of Diode-Side-Pumped Nd:YAG Laser

Highly efficient and high-power continuous-wave (CW) green beam generation by intracavity frequency doubling of diode side-pumped Nd:YAG laser using a water cooled high gray track resistant potassium titanyl phosphate crystal is demonstrated in a Z-shaped resonator design ensuring resonator stability over the entire range of the pump power with optimized spot sizes at the respective intracavity components configuration. A maximum of 82.5 W of CW green power was obtained at a total diode pumping power of 750 W, corresponding to 11% pump to green beam conversion efficiency. The green power increases linearly with pump power without any sign of power rolloff, and no damage of the crystal due to thermal lensing or gray tracking is observed. The long-term stability is excellent with ±0.7% variation in the output power. The short-term rms intensity fluctuation is measured to be ±0.2%. The performance of the laser by considering the pump-power-induced thermal lensing effect and the M² parameter at the fundamental wavelength has been analyzed. The theoretical model showed excellent agreement with the experimental results.