Development of a TiO₂/SiO₂ waveguide-mode chip for an ultraviolet near-field fluorescence sensor

Aimed at detecting fluorescent-labeled biological substances sensitively, a sensor that utilizes near-field light has attracted much attention. According to our calculations, a planar structure composed of two dielectric layers can enhance the electric field of UV nearfield light effectively by inducing waveguide-mode (WM) resonance. The fluorescence intensity obtainable by a WM chip with an optimized structure is 5.5 times that obtainable by an optimized surface plasmon resonance chip. We confirmed the above by making a WM chip consisting of TiO₂ and SiO₂ layers on a silica glass substrate and by measuring the fluorescence intensity of a solution of quantum dots dropped on the chip.