Optical and physical characterization of SiO/sub 2-x/-Al thin-film polarizer on x-cut LiNbO/sub 3/ substrate

For the purpose of a mechanical evaluation of a metal-cladding polarizer, a precise characterization of SiO/sub 2-x/-Al thin-film succession fabricated on a LiNbO/sub 3/ substrate was made as well as an experimental optimization of the SiO/sub 2-x/-Al polarizer for the Ti:LiNbO/sub 3/ waveguide. A 10-nm-thick SiO/sub 2-x/ was selected as the optimized underlay of a SiO/sub 2-x/-Al polarizer for the Ti:LiNbO/sub 3/ waveguide using a wavelength of /spl lambda/=1.55 /spl mu/m. Results of scratch testing show that the adhesive strength of SiO/sub 2-x/-Al films was almost the same level as that of Ti-Au films on a thick SiO/sub 2/ layer, commonly used for metallic underlay of Au-plated electrodes. From observing SiO/sub 2-x/-Al film using a transmission electron microscope, it was confirmed that the 10-nm-thick SiO/sub 2-x/ underlay stratified well without serious thickness fluctuation.