Electrooptic Coefficient r33 in Proton-Exchanged z-Cut LiTaO3 Waveguides

Abstract
LiTaO3 TM-mode planar optical waveguides have been fabricated on a z-cut substrate through one-step proton exchange in benzoic acid below 250°C. The effective diffusion coefficient is measured as D=D 0 exp (-E a/k T) with D 0 of 3.61×1017 µm2/h and the activation energy E a of 1.82 eV. In the single-mode waveguides, the propagation loss is as low as 0.7 dB/cm at the light wavelength of 633 nm. The electrooptic coefficient in these waveguides is measured as 28.4±0.4 pm/V at 633 nm, and almost negligible electrooptic degradation is observed compared with the bulk LiTaO3.