Mie and Bragg Plasmons in Subwavelength Silver Semi‐Shells

Abstract

2D arrays of silver semi-shells of 100 and 200 nm diameter display complex reflection and transmission spectra in the visible and near-IR. Here these spectral features are deconstructed and it is demonstrated that they result from the coupling of incident light into a delocalized Bragg plasmon, and the latter's induction of localized Mie plasmons in the arrays. These phenomena permit the excitation of transverse dipolar plasmon resonances in the semi-shells despite an ostensibly unfavorable orientation with respect to normally incident light. The resulting spectral feature in the mid-visible is strong and tunable.

Far-field disentanglement of modes in hybrid plasmonic-photonic crystals by fluorescence nano-reporters

“…These observations allow us to confirm the assignment of this mode to a localized surface plasmon polariton (LSPP) resonance. Let us note here that, besides reports in the litterature [11,32], the attribution of the inflection point in Figure 2 A to a LSPP is based on comparison with Figure 2 B, the latter being confirmed by the electric field pattern observed in Figure 3 .…”

“…A strong plasmon excitation manifests itself through a strong absorption of incident light. The inflection point around 705 nm, exhibited in the transmission spectrum of Figure 2 A and considerably red-shifted with respect to the transmission maximum, might be attributed to localized surface plasmon polariton (LSPP) resonances in the silver half-shells, which are coupled and strongly interacting at the HS rim junctions of the hybrid structure [11,32].…”

“…Another resonance in the metal-on-monolayer hybrid structure refers to localized plasmons excited in individual halfshells (HSs) [12]. Isolated silver HSs were shown to exhibit transverse (polarized parrallel to the half-shell symmetry axis) and longitudinal plasmon resonances [32]. By joining these HSs in a dense array, the longitudianl mode is suppressed.…”

Optical Properties of Thin Gold Nanoshell Arrays and Their Application as NIR SERS Substrate

“…The wavelength shift rate gets an approximate index increase as the particle spacing gap decreases, and this relationship is independence of the nanoparticle morphology, size and other factors. Moreover, the more particles get involved in coupling effect, the redder LSPR wavelength shifts [8]. In general, as far as the fabricated nanostructures are concerned, the LSPR wavelength shift contribution from the increased near field coupling interaction between particles is always stronger than the contribution from the increased shell thickness, thus the resonance wavelength moves to longer wavelength as the film thickness gets thicker.…”

Fabrication of double nano-cup assemblies and their anomalous plasmon absorption

“…This discrepancy is most likely due to the red-shifting effect of the glass substrate in the experimental sample. However, it may also be due in part to the tapered nature of the deposits in real structures [38]. The illumination responsible for the extinction of Figure 3c can be broken into various components, Figure 4a, and the effect of each tested individually.…”