Photonic analog of bilayer graphene

Drawing inspiration from bilayer graphene, this paper introduces its photonic analog comprising two stacked graphenelike photonic crystals that are coupled in the near field through spoof surface plasmons. Beyond the twist degree of freedom that can radically alter the band structure of the bilayer photonic graphene, the photonic dispersion can be also tailored via the interlayer coupling which exhibits an exponential dependence on the distance between the two photonic crystals. We theoretically, numerically, and experimentally characterize the band structures of AA- and AB-stacked bilayer photonic graphene, as well as for twisted bilayer photonic graphene with even and odd sublattice exchange symmetries. Furthermore, we numerically predict the existence of magic angles in bilayer photonic graphene, which are associated with ultraflat bands resulting from interlayer hybridization. Finally, we demonstrate that the bilayer photonic graphene at a particular twist angle satisfying even sublattice exchange symmetry is a high-order photonic topological insulator. The proposed bilayer photonic graphene could constitute a useful platform for identifying new quantum materials and inspiring next-generation photonic devices with new degrees of freedom and emerging functionality.

Automated summary

This paper presents a photonic analog inspired by bilayer graphene, with two stacked graphenelike photonic crystals coupled through spoof surface plasmons. The photonic dispersion and band structure of the bilayer photonic graphene can be tailored through interlayer coupling and twist degree of freedom, leading to the prediction of magic angles and high-order photonic topological insulators. The proposed bilayer photonic graphene could potentially lead to the discovery of new quantum materials and next-generation photonic devices.