Effects of intermediate dielectric films on multilayer surface plasmon resonance behavior

The effects of intermediate dielectric films on multilayer surface plasmon resonance (SPR) behavior were studied in terms of biosensing applications. Ten simple and complex oxides and fluoride, including MgF(2) and MgO, SiO(2), TiO(2) and complex PZT family dielectric materials, were evaluated. The materials cover a wide range of refractive indices, from 1.19 for the porous silica film to 2.83 for the TiO(2) film. The resonance curves of the multilayer SPR configurations were taken from an angular modulated Kretschmann set-up under a fixed incident wavelength of 543.5 nm. The intermediate dielectric layer has no strong effect on the SPR resonance angle and minimum reflectance at the resonance point. Some intermediate dielectric films, such as MgF(2), porous silica, TiO(2) and PLZT, apparently reduce the width of the resonance curves, resulting in sharper resonance dips. Better performance of the multilayer SPR biosensor incorporating these dielectric films is expected.