Electromagnetic fields distribution in multilayer thin film structures and the origin of sensitivity enhancement in surface plasmon resonance sensors

The performance of surface plasmon resonance (SPR) sensors depends on the design parameters. An algorithm for calculating the electromagnetic fields distribution in multilayer structure is developed relying on Abeles matrices method for wave propagation in isotropic stratified media. The correlation between field enhancement and sensitivity enhancement is examined and found to agree with the overlap integral in the analyte region. This correlation was verified in the conventional SPR sensor based on Kretschmann configuration, and in the improved SPR sensor with high refractive index dielectric top layer for several cases, e.g. field enhancement due to resonance, the sensitivity dependence on the wavelength, the influence of prism refractive index on sensitivity, and the effect of the layers materials and thicknesses.