Graphene nanoribbons: Photonic crystal waveguide analogy and minigap stripes

Abstract

Graphene nanoribbons are one-dimensional multimode systems with quasilinear electron dispersion. We discuss why they are direct analogs of broad photonic crystal waveguides. Three kinds of dispersion regions found in band structure of the latter ͑Fabry-Perot region, mini-stopband region, and coupled-zone-edge regions͒ are traced to their equivalent in zigzag graphene nanoribbons whose edges are periodically modified. For a superperiod of ϳ1 nm, the zone folding arising across the nearly linear low-energy part of the electronic dispersion induces these equivalent band structures. A last analogy is the capability to induce a form of localization characterized by minigap stripes and collective flatband edges through a limited modification localized within a pair of edge rows of the nanoribbon, representing typically less than 1% of the ribbon atoms.

Optical Excitations and Field Enhancement in Short Graphene Nanoribbons

“…Graphene has proved to have unique electronic and mechanical properties, 22 and has been more recently investigated also for photonics and optoelectronics. [23][24][25] In the field of (nano)plasmonics, so far most emphasis has been devoted to spectroscopy of plasmons in extended graphene, either doped or undoped, [26][27][28][29][30][31][32] and to the large lifetimes of their excitations compared to conventional metals. 30,33 Some interesting predictions, mostly based on macroscopic models, have been proposed for plasmonics in spatially-modulated graphene of micron and sub-micron size range.…”

Ballistic charge transport in graphene and light propagation in periodic dielectric structures with metamaterials: A comparative study

“…Although the absolute values of the transmission and reflection coefficients in Eqs. (18) and (24) are different, the dispersion characteristics of two adjoining right-and left-handed dielectric layers, and the energetic spectrum diagrams of n − p junction in graphene are identical, as it is shown schematically in Fig. 3.…”

Valley notch filter in a graphene strain superlattice: Green's function and machine learning approach

“…2(a)-(b). Due to the folding, the unstrained supercell shows crossings between modes in the same or in the opposite valley, it is important to note that the periodic potential could lift the degeneracy at these points 25 . A comparison between the left and right panels of Fig.…”

“…It is well known that one-dimensional peri-odic potentials modify the electronic properties of bulk graphene producing anisotropic charge transport 21 , additional Dirac points 22 and a tunable band gap 23,24 . In addition, in graphene nanoribbons periodicity couples transverse modes promoting selective reflection 25 . From the experimental point of view, it has been shown the impressive capacity of depositing graphene on nanopatterned substrates [26][27][28][29] ; local measurements of the electronic properties have shown the appearance of pseudo-Landau levels in the strained regions providing direct evidence of the formation of strain superlattices 26 .…”