Fabrication and characterization of titanium-indiffused proton-exchanged optical waveguides in Y-LiNbO_3

We report a systematic study of the fabrication and characterization of planar optical waveguides in Y-LiNbO3 by a process that combines titanium indiffusion and proton exchange (TIPE) techniques. Mode effective refractive-index measurements have been made on a large number of TIPE guides fabricated at various temperatures exchanged for different durations. The data have been analyzed to calculate the values of the diffusion coefficient and the activation energy for the proton exchange process in these guides. m-line scans indicate that there is a considerable amount of scattering in TIPE guides; the quality, however, improves with the increase of exchange time.