RESUMO
Waveguides in LiNbO3 are realized by a soft proton exchange (SPE) process with use of a melt of stearic acid highly diluted by lithium stearate. No phase transitions are formed when alpha-phase waveguides are obtained by SPE. The alpha-phase presents the same crystalline structure as that of pure LiNbO3 crystal, and it maintains the excellent nonlinear and electro-optical properties of the bulk material. The kinetics of the SPE method is studied by the use of secondary-ion mass spectrometry and prism-coupling techniques. The hydrogen effective diffusion coefficient as well as the self-diffusion coefficients of H+ and Li+ ions are determined as a function of the proton-exchange temperature for X-cut LiNbO3.
RESUMO
By using x-ray diffraction and optical waveguide characterization, it has been shown that proton-exchanged layers on Z-cut LiNbO(3) can have as many as seven different crystallographic phases that are stable at room temperature. This study allows us to establish some correlation between fabrication parameters and the crystalline structure, the index profiles, and the propagation losses of waveguides prepared by this process.
