Investigation of the sensing properties of a localized surface plasmon nanocavity

Surface plasmon-polariton excitations are electromagnetic modes responsible for a huge field confinement at the interface between a conductor and a dielectric. These modes mitigate light scattering even below the diffraction limit, which allows the reduction in size of several kinds of electromagnetic devices such as waveguides, resonators and sensors. Within this framework, we apply the FEM-RBCI formulation to investigate the response at the optical spectrum of a nanocavity filled with silver nanodisks. Computational simulations show that the coupling between localized surface plasmon modes excited at the periphery of the nanodisks yields a high sensitivity degree in an ultra-compact area. Such sensitivity is nearly constant and covers a wide range of refraction indexes of the surrounding medium. Furthermore, it is not required any external phase matching technique to achieve surface plasmon resonance. These characteristics demonstrates the great potential of the structure to improve optical sensing applications.