Abstract
We present a nonlinear characterization of annealed-proton-exchange lithium niobate channel waveguides in view of their application for wavelength shifting in wavelength division multiplexing systems. We exploit second harmonic generation as a very sensitive technique to test waveguide uniformity and optical quality. The experimental results are successfully compared with those obtained using numerical simulations based on the finite element method. The analysis suggests useful criteria for the optimization of the fabrication parameters in order to enhance the efficiency of wavelength conversion processes.