Hybrid Ni/SiO2/Au dimer arrays for high-resolution refractive index sensing

Abstract

Abstract:We introduce a novel magnetoplasmonic sensor concept for sensitive detection of refractive index changes. The sensor consists of a periodic array of Ni/ SiO 2 /Au dimer nanodisks. Combined effects of near-field interactions between the Ni and Au disks within the individual dimers and far-field diffractive coupling between the dimers of the array produce narrow linewidth features in the magneto-optical Faraday spectrum. We associate these features with the excitation of surface lattice resonances and show that they exhibit a spectral shift when the refractive index of the surrounding environment is varied. Because the resonances are sharp, refractive index changes are accurately detected by tracking the wavelength where the Faraday signal crosses 0. Compared to random distributions of pure Ni nanodisks or Ni/SiO 2 /Au dimers or periodic arrays of Ni nanodisks, the sensing figure of merit of the hybrid magnetoplasmonic array is more than one order of magnitude larger.

Magnetoplasmonic properties of perpendicularly magnetized [Co/Pt]N nanodots

“…2 demonstrate that [Co/Pt] N nanodot arrays support the excitation of intense SLRs if D ≥ 150 nm and N ≥ 5. The minimal SLR linewidth is about 100 nm, which is comparable to that of previously studied magnetoplasmonic arrays made of Ni nanodisks 24,25,38 or Au/SiO 2 /Ni dimers 38 .…”

Geometric frustration in a hexagonal lattice of plasmonic nanoelements

“…Moreover, the optical response of the system may also be governed by the near-field coupling between nearest neighbors giving rise to Localized Surface Resonances (LSR). Whereas LSR usually exhibit broad extinction peaks due to radiative damping, SLR present sharp linewidths that could be more suitable for applications profiting from a high frequency specificity [21][22][23][24][25]. Interestingly, for incoming radiation around normal incidence and with a wavelength matching one of the diffraction edges of the Bravais lattice of the array, a SLR mode due to the lattice diffraction shows up.…”

Coupling phenomena and collective effects in resonant meta-atoms supporting both plasmonic and (opto-)magnetic functionalities: an overview on properties and applications [Invited]

“…It has been proven that nanostructure design [ 151], phase-sensitive detection schemes [73,112,152] and ordering of plasmonic nanoparticles into a regular array [153,154] can be used to enhance the sensing figure of merit (FoM), which is a parameter defining the sensor performance and is equal to the ratio between the sensitivity of the resonance (shift of the LSPR peak ∆λ divided by the refractive index change ∆n or by the thickness ∆t of the molecules adsorbed by the meta-atom surface) and the FWHM of the resonance [ 155 -158 ]. Pourjamal et al [ 159 ] combined all these aspect in one system, demonstrating that the hybrid magneto-plasmonic crystal studied in ref. [147] can be used for high-resolved and enhanced sensing of refractive index changes, proving experimentally that, compared to random distributions of pure Ni nano-disks or Ni/SiO2/Au dimers or periodic arrays of Ni nano-disks, this hybrid system displays one order of magnitude larger sensing FoM.…”