Dual-mode tunable absorber based on quasi-bound states in the continuum.

In this Letter, we propose a novel, to the best of our knowledge, dual-mode tunable absorber that utilizes quasi-bound states in the continuum (q-BIC) based on the periodically arranged silicon cylinders tetramer. By introducing asymmetry perturbation through manipulating the diameters of diagonal cylinders in the all-dielectric structure, the symmetry-protected BIC (SP-BIC) transforms into q-BIC, leading to the emergence of one transmission and one reflection Fano-like resonant mode. The relationship between the quality factor of each mode and the asymmetry parameter α is analyzed, revealing an exponential dependence with an exponent of -1.

Topological plasmons in stacked graphene nanoribbons.

In this Letter, we theoretically study the topological plasmons in Su-Schrieffer-Heeger (SSH) model-based graphene nanoribbon (GNR) layers. We find that for the one-dimensional (1D) stacked case, only two topological modes with the field localized in the top or bottom layer are predicted to exist by the Zak phase. When we further expand the stacked 1D GNR layers to two-dimensional (2D) arrays in the in-plane direction, the topology is then characterized by the 2D Zak phase, which predicts the emergence of three kinds of topological modes: topological edge, surface, and corner modes.

Toroidal resonance based optical modulator employing hybrid graphene-dielectric metasurface.

In this paper, we demonstrate the combination of a dielectric metasurface with a graphene layer to realize a high performance toroidal resonance based optical modulator. The dielectric metasurface consists of two mirrored asymmetric silicon split-ring resonators (ASSRRs) that can support strong toroidal dipolar resonance with narrow line width (~0.77 nm) and high quality (Q)-factor (~1702) and contrast ratio (~100%).

Multi-band perfect plasmonic absorptions using rectangular graphene gratings.

We propose to achieve multi-band perfect plasmonic absorptions with peak absorptivity >99% via the excitation of standing-wave graphene surface plasmon polaritons using single-layer graphene-based rectangular gratings. For the case with continuous gratings, perfect absorptions are only allowed for even-order modes, while the absorptions are quite low for odd-order modes because the fields are out-of-phase. However, for gratings with bottom-open configuration, four-band perfect absorptions containing both the even- and odd-order modes can be realized, which are found to be highly sensitive to the incident angle.

Localized plasmonic field enhancement in shaped graphene nanoribbons.

Graphene nanoribbon (GNR), as a fundamental component to support the surface plasmon waves, are envisioned to play an important role in graphene plasmonics. However, to achieve extremely confinement of the graphene surface plasmons (GSPs) is still a challenging. Here, we propose a scheme to realize the excitation of localized surface plasmons with very strong field enhancement at the resonant frequency.

Excitation of crest and trough surface plasmon modes in in-plane bended graphene nanoribbons: erratum.

An erratum is presented to correct the typing mistake in a equation in Sect. 3.1 of [Opt.

Graphene-based long-range SPP hybrid waveguide with ultra-long propagation length in mid-infrared range.

A graphene-based long-range surface plasmon polariton (LRSPP) hybrid waveguide, which is composed of two identical outer graphene nanoribbons and two identical inner silica layers symmetrically placed on both sides of a silicon layer, is investigated using the finite-difference time-domain method. By combining the simulated results with the coupled mode perturbation theory, we demonstrate that the LRSPP and short-range SPP (SRSPP) modes originate from the coupling of the same modes of the two graphene nanoribbons. For the LRSPP mode, an ultra-long propagation length (~10 μm) and an ultra-small mode area (~10A, where A is the diffraction-limited mode area) can be simultaneously achieved.

Excitation of crest and trough surface plasmon modes in in-plane bended graphene nanoribbons.

To achieve efficiently coupling to external light is still remaining an insurmountable challenge that graphene faces before it can play an irreplaceable role in the plasmonic field. Here, this difficulty is overcome by a scheme capable of exciting graphene surface plasmons (GSPs) in in-plane bended gratings that are formed by elastic vibrations of graphene nanoribbons (GNRs). The gratings enable the light polarized perpendicularly to the GNRs to two kinds of GSP modes, of which the field concentrations are within the grating crest (crest mode, C-M) and trough (trough mode, T-M), respectively.