Modal overlap analysis of propagation modes in PPLN ridge waveguide

In order to study effect of modal overlap coefficients on conversion efficiency in lithium niobate waveguide,propagation modes and difference frequency generation conversion efficiency were studied with finite difference method.The mode field distributions of 1560nm and 780nm waves and the modified wavelength conversion introduced by mode overlap coefficients were obtained.The modified theoretical results were consistent with the experimental ones and the optimal ridge waveguide size was achieved.The calculated results can provide guide for design of direct bonded periodically poled lithium niobate ridge waveguide with nonlinear interaction.