Nonlinear optical properties of (H+,He+)-implanted planar waveguides in z-cut lithium niobate:: annealing effect

Reflection second-harmonic generation from the polished waveguide end face was used to investigate the nonlinear properties of LiNbO3-implanted waveguides fabricated by use of 2-MeV He+ and 1.5-Mev H+ beams. Results were compared with waveguides obtained by protonic exchange in benzoic acid, In contrast to the exchanged sample where the nonlinearity is strongly reduced, the implanted samples showed that the guiding region presents rather the same response as the substrate. The area where the optical barrier is located showed a strongly enhanced second-harmonic signal that was likely to be due to structural modifications in this area. Moreover, the investigation of the annealing effect showed strong interaction of protons with the lattice compared with that of He+ ions. (C) 2001 Optical Society of America.