We formed planar waveguides in LiNbO<sub>3</sub> and LiTaO<sub>3</sub> crystals by megaelectron volt He-ion implantation. The dark modes of both waveguides are measured and their refractive-index profiles are described according to the parameterized index profile reconstruction method. The extraordinary indices of both ion-implanted waveguides exhibit quite different profiles. We compare the thermal stability of barriers in ion-implanted LiNbO<sub>3</sub> and LiTaO<sub>3</sub> waveguides by annealing at different temperatures. The results show that the barrier in a LiTaO<sub>3</sub> planar waveguide has higher thermal stability than that in a LiNbO<sub>3</sub> waveguide. The experiments also show that annealing at a temperature higher than 400 °C results in recrystallization of the barrier.
© 1999 Optical Society of America
Fei Lu, Feng Xiang Wang, Wei Li, Jian Hua Zhang, and Ke Ming Wang, "Annealing Behavior of Barriers in Ion-Implanted LiNbO3 and LiTaO3 Planar Waveguides," Appl. Opt. 38, 5122-5126 (1999)