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Electric control of spin orbit coupling in graphene-based nanostructures with broken rotational symmetry

Research output: Contribution to journalArticle

Alessandro Ciattoni , Anatoly Zayats, Claudio Conti, Andrea Marini

Original languageEnglish
JournalLaser and Photonics Reviews
Accepted/In press15 Jun 2020

King's Authors

Abstract

Spin and angular momenta of light are important degrees of freedom in nanophotonics which con-trol light propagation, optical forces and information encoding. Typically, optical angular momen-tum is generated using q-plates or spatial light modulators. Here, we show that graphene-supported plasmonic nanostructures with broken rotational symmetry provide a surprising spin to orbital an-gular momentum conversion, which can be continuously controlled by changing the electrochemical potential of graphene. Upon resonant illumination by a circularly polarized plane wave, a polygo-nal array of indium-tin-oxide nanoparticles on a graphene sheet generates scattered field carrying electrically-tunable orbital angular momentum. This unique photonic spin-orbit coupling occurs due to the strong coupling of graphene plasmon polaritons and localised surface plasmons of the nanoparticles and leads to the controlled directional excitation of graphene plasmons. The tuneable spin-orbit conversion pave the way to high-rate information encoding in optical communications, electric steering functionalities in optical tweezers, and nanorouting of higher-dimensional entangled photon states.

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