Angular Piecewise Modal Analysis for Waveguide-Coupled Surface Plasmon Resonance Structure

Resonance response of waveguide-coupled surface plasmon resonance (WCSPR) structure is investigated numerically in a piecewise manner. The 2-D reflectance and phase along with the phase response circle (PRC) and complex amplitude reflection Argand diagram in angular interrogation is demonstrated for homo- and hetero bimetallic nanofilm. The gradual appearance of waveguide resonance with increasing thickness of the waveguide layer provides significant information about the coupling of waveguide and plasmonic resonance which is much needed for the choice of correct device parameters. Moreover, magnetic field enhancement is also studied for each different mode in angular piecewise manner with variations in metal layers as well as variations in WG layer using different conventional optical polymers. Angular piecewise differential phase gives some insight into the application of chemical and biological sensing and can provide an improved sensitivity by direct imaging of the fringe pattern due to the change in refractive index of the sensing medium.