A two-pass quadrature scheme using (CLBO) crystals was used to frequency double a Nd:YAG laser with high efficiency with tens of watts of average output power and low input laser intensities. The 532-nm bidirectional output of this scheme is readily suited for pumping Ti:sapphire crystals, making it possible to build compact high-power chirped-pulse amplification systems. Using this scheme, we obtained 2.73 J of second-harmonic pulse energy from 3.27 J of input 1064-nm fundamental laser pulse energy at a modest intensity of 330 MW/cm2 and 10 Hz, corresponding to an energy-conversion efficiency of 83%. We discuss in detail the design and performance of this frequency-conversion scheme in terms of output parameters, stability, and scalability.
© 2002 Optical Society of America