Optical interactions in ZnO-TeO2 bi-layer for AO device applications

A bi-layer structure using amorphous TeO₂ and piezoelectric ZnO thin film has been grown by reactive rf sputtering on corning glass (cg) substrate to investigate its compatibility for an acousto-optic (AO) device. Initially TeO_2-x films were grown at different oxygen partial pressures and, structural and optical characterizations were performed to optimize the O₂ gas pressure. Effect of post-deposition annealing was studied for achieving low optical loss. Optical waveguiding was observed by prism coupling technique and the loss measurements were done. Subsequently, a high quality c-axis oriented ZnO film was grown, which is known to be suitable for SAW propagation. Finally, a TeO₂-ZnO bi-layer was grown with a clean interface and optical waveguiding was observed. Implications related to large thickness of ZnO have been discussed and a better alternate feasible TeO₂-ZnO structure is proposed.