Influence of Temperature on Reflectivity of Symmetrical Metal-Cladding Optical Waveguide

The influence of temperature on the reflectivity of symmetrical metal-cladding optical waveguide (SMCOW) is studied theoretically by means of single-factor investigation under spectral and angular interrogation mode of operation. The theoretical model for temperature dependence of reflectivity includes the temperature dependence of refractive index and thickness of guiding layer, the temperature dependence of the metal film thickness and metal-dielectric function. It is found that the effect of temperature on the reflectivity of SMCOW is mainly attributed to the temperature dependence of refractive index and thickness of guiding layer; on the contrary, the temperature properties of metal film hardly contribute to the influence of temperature on the reflectivity. Based on the analysis, the sensitivities of SMCOW with guiding layer made up of different optical glasses are computed under both spectral and angular interrogation. This letter is supposed to provide direction in designing SMCOW sensors against the temperature variation.