Sol-gel derived optical waveguide films: technological platform for development of planar evanescent wave sensors

Abstract

Plane evanescent wave sensors are being developed for over thirty years. However, their full development is somehow limited by the lack of relatively cheap and stable waveguide layers of high refractive index, low optical losses and at the same time resistance to the impact of chemical substances. The paper involves waveguide layers SiO2:TiO2 of high refractive index (∼1.81) satisfying these criteria, fabricated via sol-gel method and dip-coating technique. The parameters of the waveguide layers SiO2:TiO2 were determined using elipsometric and spectrophotometric methods. The presented waveguide layers have excellent optical properties and are suitable for the application in the planar evanescent wave sensors technology. For the best waveguide SiO2:TiO2 layers, the obtained level of optical loss was below 0.2 dB/cm.