Electro-optic effect in proton exchanged LiNbO/sub 3/ and LiTaO/sub 3/ waveguides

Electro-optic properties of proton-exchanged (PE) waveguide layers in LiTaO/sub 3/ and LiNbO/sub 3/ are studied and related to their optical characteristics. The proton-exchange process induces a degradation of the electro-optic activity in both types of waveguides, PE LiNbO/sub 3/ and PE LiTaO/sub 3/. The measured electro-optic effect is close to the detection sensitivity even when the exchange regime is performed at low temperatures for short periods of time. The PE samples have been annealed (APE waveguides) and the changes of their r/sub 33/ electro-optic coefficient has been followed at successively higher temperatures and periods of time. Subjected to annealing at temperatures between 265-420/spl deg/C, the LiTaO/sub 3/ layers show a partially recovered r/sub 33/ coefficient, the recovering being different for quick and slow cooling of the samples. In thin APE LiNbO/sub 3/ waveguiding layers a restoration of r/sub 33/ up to 75% of the bulk value is observed due to the annealing at temperatures between 200-340/spl deg/C.