Subnanometer-Resolution Nanoparticle Sensing through the Strong Coupling between Surface Plasmon Polariton Whispering Gallery Resonances and Localized Surface Plasmon

High-resolution nanoparticle sensing is very important, and many schemes have been proposed to achieve this goal. Circular nanocavities in which surface plasmon polariton (SPP) whispering gallery mode (WGM) resonances were excited designed sense particles of ultra-small size with high resolution. Localized (LSPRs) when a metal particle was set the circular cavity. The SPP WGM split into symmetric (SM) antisymmetric (ASM) due LSPRs scattering SPPs. strong coupling between SM resonance generated positive opposite modes, sensitive variation position. Even small nanometer-sized introduced produced splitting. splitting induced by reduced limit. simulation results show that 1 nm changes radius position led 11.8 10.2 wavelength shifts, respectively. This means variations 0.09 0.1 can be sensed spectral applied at subnanometer