Response Properties of Waveguide-Optic Evanescent Field Refractive Index Sensors According to Titanium Dioxide Thin Film Conditions

Abstract

This study examined the response properties of a high-sensitivity waveguide-optic evanescent field refractive index sensor according to the conditions used to deposit the titanium dioxide (TiO(2)) thin film. Rib-type silica waveguides were fabricated by plasma enhanced chemical vapor deposition, photolithography and plasma etching. The conditions, such as the thickness and length of a TiO(2) thin film on the silica waveguides, were controlled using a metal shadow-mask and the sputtering deposition parameters. The polarimetric interference patterns generated through an interaction between the waveguide and a glycerol solution showed a change in the degree of evanescent field strength according to the TiO(2) thin film deposition conditions. The results suggest that the sensitivity of the fabricated device can be improved by increasing the thickness (maximum-35 nm) and length of the TiO(2) thin film on the optical waveguide.