Plasmonic nanoantennas on Epsilon-Near-Zero Metamaterial substrates

Abstract

The localized surface plasmon resonance (LSPR) is used for light confinement within sub-wavelength scale. The fields are localized and re-directed with the metal nanoantennas. The localization of electric field inside and outside of such a nanoantenna depends upon its shape, the metal, and substrate. Therefore, it is possible to tailor the resonant wavelength by changing the nanoantenna parameters. In this thesis, I have used epsilon-near-zero (ENZ) metamaterial as a substrate to dictate the LSPR of golden (Au) nanodisk (ND) antenna arrays. The hyperbolic metamaterial (HMM), which consists of metal and dielectric alternating layers, designed to have an effective permittivity (epsilon) close to zero. The ENZ substrate with almost zero index slows down the resonance shift of NDs which is known as "pinning effect". I have experimentally demonstrated the pinning effect, by comparing the transmission of ND antennas on glass to the transmission of NDs on HMM with ENZ wavelength at 684 nm. The NDs on HMM substrate have three times less spectral shift compare to the NDs on glass. The robust control of LSPR with ENZ metamaterial substrate can be applied in emission enhancing and beam steering.