Theoretical and experimental investigations of surface plasmon waveguide structures for sensing a

摘要

Abstract: Highly sensitive surface plasmon waveguide devices capable of detecting changes in the refractive index of the surrounding environment on the order of 10$+$MIN@5$/ have been designed. Inclusion of a high refractive index dielectric layer in the structure allows the spectral response of the plasmon resonance to be tuned over a wide range of wavelengths. A preliminary experimental characterization of these devices has been carried out using air, water, and Nafion fluoropolymer as superstrate materials. Results indicate that surface roughness in the metal layer degrades the extinction ratio, but does not alter the resonance wavelength. In addition, a design for a more durable surface plasmon waveguide sensor, in which the metal layer is protected, is proposed.!5