Pseudospin-2 in photonic chiral borophene

TL;DR

This paper explores a photonic chiral borophene with pseudospin-2 conical intersections, revealing unique quasiparticles, conical diffraction, and topological effects like high-charge optical vortices, advancing understanding of photonic topological materials.

Contribution

It introduces a photonic chiral borophene with pseudospin-2 degeneracy and demonstrates related topological phenomena and optical vortex generation.

Findings

Observation of pseudospin-2 conical intersection

Conical diffraction and pseudospin-orbit interaction in photonic borophene

Generation of highly charged optical phase vortices

Abstract

Pseudospin is an angular momentum degree of freedom introduced in analogy to the real electron spin in the effective massless Dirac-like equation used to describe wave evolution at conical intersections such as the Dirac cones of graphene. Here, we study a photonic implementation of a chiral borophene allotrope hosting a pseudospin-2 conical intersection in its energy-momentum spectrum. The presence of this fivefold spectral degeneracy gives rise to quasiparticles with pseudospin up to $\pm2$. We report on conical diffraction and pseudospin-orbit interaction of light in photonic chiral borophene, which, as a result of topological charge conversion, leads to the generation of highly charged optical phase vortices.