Multimode integrated optical sensor based on absorption due to resonantly coupled surface plasmons

摘要

Abstract: The coupling of p-polarized waveguide modes into waveguide- surface plasmon coupled modes is a promising concept to combine the features of propagating waveguide modes with the resonant field enhancement of surface plasmons. We demonstrate a waveguide device which allows to couple more than one TM mode to the surface plasmon. For a given waveguide device and a fixed laser wavelength the development of the imaginary part, K, of the propagation constant, N$-eff$/, of the waveguide-surface plasmon coupled modes are simulated and the results are compared with experimental results. The waveguide losses are in perfect agreement with the simulations. Due to the resonant nature of the waveguide-surface plasmon coupled modes, which was found by the simulations, the waveguide attenuation is very sensitive to the refractive index of the subphase outside of the waveguide structure. This resonant behavior could be confirmed experimentally.!22