Generation of high-power blue light in periodically poled LiNbO₃

We report the generation of 450-mW average blue (473-nm) power by frequency doubling of a diode-pumped 946-nm Nd:YAG laser. We achieved pulsed operation at a high repetition rate (~160 kHz) by driving the relaxation oscillations of the laser. A 40% conversion efficiency to the second harmonic was obtained in a single-pass, extracavity, first-order, quasi-phase-matched process in which periodically poled lithium niobate (period 4.5 mm, thickness 0.5 mm, and length 15 mm) at 140 ±C was used. The resulting high-power blue beam was circular in profile and nearly diffraction limited, indicating that photorefractive effects do not appear to limit device performance.