All-solid D-shaped photonic fiber sensor based on surface plasmon resonance

We propose and investigate an all-solid photonic fiber with D-shaped structure based surface plasmonic resonance sensor using a FEM (Finite element method) with PMLs (perfectly matched layers) boundary conditions. This sensor can resolve phase-matching problem and simplify the production process. Simulation results show increasing shifts in resonance wavelength for the same index change, so the refractive index sensitivity of at least 7300 nm/RIU (refractive index unit) can be achieved and 216 for FOM (figure of merit). Then, we study the effect of size variation of the thicknesses of a silver coating, first layer rods, as well as polishing depth, with a view of tuning and optimizing plasmon excitation by the core-guided mode. We observe a unique phenomenon that the resonant wavelength red shifts at first and then blue shifts with the polishing depth increasing, and the FOM achieves maximum at watershed wavelength. The sensor demonstrates narrower resonance spectral width, improves the sensing performance in terms of signal to noise ratio (SNR), and shows a better detection limit. (C) 2011 Elsevier B.V. All rights reserved.