Tuning resonant optical transmission of metallic nanoslit arrays with embedded microcavities

We numerically study the characteristics of optical transmission of metallic nanoslit arrays (MNSAs) with embedded microcavities (MC-MNSAs) and demonstrate that passbands of the transmission spectra can be monotonously tuned by adjusting the dimensions of the microcavities. The study discloses that spectra of conventional MNSAs and MC-MNSAs are determined mainly by cavity resonances of the slits or embedded microcavities, modified by in-plane surface-plasmon wave resonances. It is also found that coupling of cavity resonances between neighboring slits or microcavities has considerable effects on the passbands. The MC-MNSA structure is shown to have potentials in applications of tunable filter arrays.