3.5 watt cw 532 nm radiation by resonant external cavity SHG of an 8.5 watt Nd:YAG laser in LBO

Second harmonic generation efficiency can be enhanced by placing the nonlinear crystal in an external cavity that resonates the fundamental, or the second harmonic or both1. Results of early efforts were disappointing due to poor quality nonlinear materials and multi-mode pump sources. Recently, as a result of advances in both nonlinear crystal growth and diode-pumped solid state laser development, efficient second harmonic generation in an external resonant cavity at power levels of tens of milliwatts has been realized2,3. As the power level of stable, single frequency lasers continues to increase, there arises the possibility of producing watt-level second harmonic radiation. In this work, we report the generation of 3.5 watts of continuous wave 532 nm radiation by frequency doubling the 8.5 watt output of an injection-locked Nd:YAG laser.