Optical and physical characterization of SiO2-x-Al thin-film polarizer on x-cut LiNbO3 substrate

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 S iO2-x-Al polarizer for the Ti:LiNbO3 waveguide. A 10-nm-thick SiO2-x was se lected as the optimized underlay of a SiO2-x-Al polarizer for the Ti:LiNbO3 waveguide using a wavelength of lambda = 1.55 mum. Results of scratch test ing 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 metal lic underlay of Au-plated electrodes. From observing SiO2-x-Al film using a transmission electron microscope, it was confirmed that the 10-mm-thick Si O2-x underlay stratified well without serious thickness fluctuation.