Abstract

We have previously reported for the first time an increase of the surface extraordinary refractive index after annealing in H⁺:LiTaO₃ optical waveguides fabricated in benzoic acid or pyrophosphoric acid [1]. This anomalous index increase is thought to be caused by a movement of protons in a unit cell [2, 3]. Recently, we have also reported that the higher surface index was observed for waveguides proton-exchanged in diluted benzoic acid when compared with those fabricated using neat benzoic acid [3]. In this paper, we investigate the effects of melt dilution on the properties of H⁺:LiTaO₃ waveguides by examining the effective index, measuring the electrooptic coefficient $r_{33}^{\text{T}}$, and performing XRC analysis and IR absorption spectroscopy.

© 1992 Optical Society of America