In-plane illuminated metallic annular aperture array for sensing application

We propose here an application to sensing of annular aperture arrays (AAA). We theoretically investigate the optical properties of the reflective AAA device when illuminated in-plane. The cavity presents almost perfect absorption due to the waveguide mode resonance with strong field localization in the aperture. Additionally, the reflective cavity is modeled to be available for on-chip sensing with a theoretically expected sensitivity of 764 nm∕RIU (refractive index unit).