Second harmonic generation of green light in a periodically poled lithium niobate waveguide

Frequency doubling in a lithium niobate optical waveguide is an attractive method for the generation of coherent visible radiation. To date, such devices have involved birefringent phase matching or the Cherenkov effect. We report quasiphase matched frequency doubling in a lithium niobate waveguide accomplished through the periodic reversal of the nonlinear coefficient.