Symmetry Decomposed Multiple Multipole Program Calculation of Plasmonic Particles on Substrate for Biosensing Applications

Plasmonic nano particles on a glass substrate with various coating layers are investigated by the Multiple Multipole Program (MMP). The rotationally symmetric geometry of these structures is broken by the obliquely incident plane wave illumination. It is shown that numerically much more efficient axi-symmetric models can still be applied for the computation of the resonance peak positions when the illumination is decomposed in its symmetry-adapted terms. The validity of this procedure was demonstrated for 100 nm gold particles with silicon oxide coating layers of different thicknesses by comparing the scattering spectra of symmetry decomposed models, full 3D models, and experiments.