Theoretical modeling of lossy mode resonance based refractive index sensors with ITO/TiO₂ bilayers

A lossy mode resonance (LMR) based fiber optic refractive index (RI) sensor utilizing indium tin oxide (ITO)/titanium dioxide (TiO₂) bilayers has been theoretically investigated. Specifically, the effect of different thickness ratios of bilayers on the sensitivity to surrounding medium RI variations was studied. It was observed that for a specific thickness ratio, a two fold increase in sensitivity can be achieved in comparison to conventional LMR sensors using a single absorbing thin film. The sensitivity can be enhanced by tuning the total bilayer thickness and bilayer thickness ratio for the desired application, which is not possible in conventional LMR sensors.