Characterization of vapor diffused Zn:LiTaO3 optical waveguides

Diffusion and optical properties of planar waveguides produced in LiTaO₃ by a recently developed technique that utilizes Zn diffusion from vapor phase are presented. The waveguides are obtained by 6-h diffusion at temperatures as low as 800°C. The results indicate that Zn is a fast diffusant in LiTaO₃ and has activation energies that are slightly less than those for Ti diffusion into LiTaO ₃. The diffusion temperatures for Zn are much lower than the 1150-1200°C require for Ti metal indiffusion. The diffusion coefficient of Zn at 800°C, is comparable to that of Ti at 1200°C. The resulting waveguides support both ordinary and extraordinary modes of polarization. The low temperature diffusion slows out diffusion and has been shown to be advantageous for making low-loss optical waveguides in LiTaO₃