Plasmonic sensor with high figure of merit based on differential polarization spectra of elliptical nanohole array.

Using the difference of the polarization transmission spectra of elliptical nanohole arrays (ENAs), the figure of merit (FOM) of the sensor performance of ENA can be significantly improved, and is inversely proportional to the measurement resolution. By optimizing the aspect ratio of the elliptical holes, Ag thickness, substrate-effect, and adhesive layer, the sensitivity, FOM, and relative sensitivity of the ENA can be improved to be 775 nm RIU, 705 RIU, and 70.23%, respectively, with an excellent linear dependence on the change of refractive index. Such a high-performance sensor also can be used in monitoring the molecule adsorption and RNA hybridization, revealing a highly localized near-field enhancement. This will benefit the sensing of surface-specific binding events in biologic detection and medical diagnosis.