To investigate the interaction between the TE and TM polarized evanescent waves and the plasmonic nanoparticles attached to the OCB surface, FDTD calculations were carried out based on the simplification depicted in Figure . Figure shows plots of the electric field intensity around AuAg NPs as they are excited by the evanescent field of TE or TM polarized light propagating in the waveguide beneath the nanoparticles. Excitation with the TE mode leads to symmetric field intensity concentrated at the north and south poles of the particles and nodes around the equator of particles. TE polarization (Figure ) lies in the xy plane oriented in the direction of the double-headed white arrow. For TM excitation, the electric field oscillates orthogonal to the xy plane. The field intensity concentrates around the equator of the nanoparticles and has lower intensity at the surface than that shown for the TE response. Particles isolated far enough apart show undistorted dipolar field intensity. For both polarizations, as the interparticle separation decreases, one observes distortions in the fields. With decreasing separation (bottom center, Figure ) one observes the high concentrations of field intensity that are the hallmark of the "hotspots" that are associated with enhanced SERS . TE and TM polarized light exhibit different transmission losses as the light propagates in asymmetric metal-clad thin-film-clad waveguides . Attenuation experienced by the TM mode is greater than that of the TE mode (Figure ) because the TM mode interacts strongly with the metal surface, while the TE mode is repelled by the metal surface . The plasmonic particles on the OCB behave as a polarization mode filter. The discontinuous nature of the plasmonic AuAg NP overlayer allows us to propagate either polarization over distances larger than would be capable with a continuous metal film.