Abstract

Parametric fluorescence, amplification, and oscillation in PPLN waveguides have already been demonstrated.^1,2 In all previous experiments, the measured efficiencies were smaller than the theoretically predicted values since the waveguide fabrication process utilized, annealed proton exchange (APE) can reduce or even destroy the nonlinear coefficient and/or the periodic domain orientation^3,4 in a portion of the guiding structure. In the experiment reported here, we used a 2 cm long, Z-cut PPLN with a 18 μm domain inversion period. The waveguides are created using a direct proton exchange process in a highly diluted melt, which induces no crystallographic phase transition.³ This allows preserving both the nonlinear coefficient and the domain orientation while fully benefiting from the power confinement associated with the guided wave configuration.

© 1999 Optical Society of America