Spin–orbit coupling in photonic graphene

Abstract

We generate experimentally a honeycomb refractive index pattern in an atomic vapor cell using electromagnetically-induced transparency. We study experimentally and theoretically the propagation of polarized light beams in such "photonic graphene".We demonstrate that an effective spin-orbit coupling appears as a correction to the paraxial beam equations because of the strong spatial gradients of the permittivity. It leads to the coupling of spin and angular momentum at the Dirac points of the graphene lattice. Our results suggest that the polarization degree plays an important role in many configurations where it has been previously neglected.

Singular flat bands

“…In this kind of artificial systems, the singular flat band can be realized more ideally than the electronic systems because of their wide controllability. For example, if the kagome lattice is realized in the photonic crystal, one can easily make t 2 smaller by increasing the lattice constant, and λ can be also varied by controlling the coupling between the medium and light polarization [163][164][165][166]. We expect that one might also study the quantum distance origin of the anomalous Landau levels of the singular flat band by applying the artificial magnetic field to the singular flat band in these artificial systems.…”

From the topological spin-Hall effect to the non-Hermitian skin effect in an elliptical micropillar chain

“…The inherent non-Hermitian nature of the polaritons has lead to the realization of exceptional points [51,52], non-Hermitian topological phases [52,53], and other related theoretical predictions [54][55][56]. The spin-orbit coupling due to the TE-TM splitting inside the microcavity has played a vital role in obtaining nontrivial spin related effects, such as the optical spin Hall effect [57][58][59], meron polarization textures [65], nontrivial bands with spin orbit interaction Hamiltonians [60][61][62][63][64][65][66][67].…”

From the Topological Spin-Hall Effect to the Non-Hermitian Skin Effect in an Elliptical Micropillar Chain

“…Their finite lifetime, sensitivity to external fields, strong nonlinearity inherited from excitons, and spin polarizations make them ideal for studying both the Hermitian and non-Hermitian topological phases. Polariton Chern insulator analogues relying on Zeeman splitting and TE–TM splitting are well-established. − Nonlinear topological polaritons have also been an intense area of research, − where in some cases the nonlinearity alone induces topological behavior. − The inherent non-Hermitian nature of the polaritons has led to the realization of exceptional points, , non-Hermitian topological phases, , and other related theoretical predictions. − The spin–orbit coupling due to the TE–TM splitting inside the microcavity has played a vital role in obtaining nontrivial spin related effects, such as the optical spin-Hall effect, − Meron polarization textures, and nontrivial bands with spin orbit interaction Hamiltonians. − …”