SENSITIVITY ANALYSIS OF COUPLED PLASMON FIBER MODE PROPAGATION FOR EVANESCENT-WAVE-SENSING

In properly tailored metal-coated optical fibers, certain waveguide modes can couple to a surface-plasmon supported by the metal coating forming combined guided field excitations. The hybrid character of these excitations combines the flexibility of guided mode propagation with the strong field enhancement at the metal-cladding interface providing a high potential for monitoring the optical properties in close proximity of the interface, i.e. the refractive index change induced by a thin analyte-adlayer. In this numerical study we outline the design-steps towards an optimized fiber-configuration as a core element of an optical sensor using a powerful mode-solver technique based on the exact solution of Maxwell's equations. The detection of the hybrid-mode resonance will be performed by monitoring the spectral absorption of the multi-layer-fiber.