Modeling of surface plasmon resonance in a bent single-mode metallized optical fiber with a finite element method

In this paper, we present a numerical study of surface plasmon resonance (SPR) excitation in a bent single-mode optical fiber with metallized cladding. It is shown that with a suitable combination of the bending radius and metal film thickness, surface plasmon waves can be excited in the film as a result of coupling between the fundamental and surface plasmon modes via whispering gallery modes (WGM) supported by the bent fiber cladding. The coupling brings about a dip in the transmission spectrum at the resonant wavelength which is strongly dependent on the ambient refractive index, thus, making it possible to build an SPR- refractometer based on a single-mode fiber without breaking the structural integrity of the fiber or using any additional elements. The refractometric sensitivity of ~12 mm/RIU are demonstrated.