For the purpose of a mechanical evaluation of a metal-cladding polarizer, a precise characterization of SiO2-x-Al thin-film succession fabricated on a LiNbO3 substrate was made as well as an experimental optimization of the SiO2-x-Al polarizer for the Ti: LiNbO3 waveguide. A 10-nm-thick SiO_SiO2-x was selected as the optimized underlay of a SiO2-x-Al polarizer for the Ti: LiNbO3 waveguide using a wavelength of =1.55 m. Results of scratch testing show that the adhesive strength of SiO2-x-Al films was almost the same level as that of Ti-Au films on a thick SiO2 layer, commonly used for metallic underlay of Au-plated electrodes. From observing SiO2-x-Al film using a transmission electron microscope, it was confirmed that the 10-nm-thick SiO2-x underlay stratified well without serious thickness fluctuation.
Yasuyuki Miyama and Hirotoshi Nagata, "Optical and Physical Characterization of SiO2-x-Al Thin-Film Polarizer on x-Cut LiNbO3 Substrate," J. Lightwave Technol. 19, 1051- (2001)