UCL Discovery

## Optically and Electrically Tunable Dirac Points and Zitterbewegung in Graphene-Based Photonic Superlattices

Deng, H; Ye, F; Malomed, BA; Chen, X; Panoiu, NC; (2015) Optically and Electrically Tunable Dirac Points and Zitterbewegung in Graphene-Based Photonic Superlattices. [Rapid communication]. Physical Review B , 91 , Article 201402(R). 10.1103/PhysRevB.91.201402.

## Abstract

We demonstrate that graphene-based photonic superlattices provide a versatile platform for electrical and all-optical control of photonic beams with deep-subwavelength accuracy. Specifically, by inserting graphene sheets into periodic metallo-dielectric structures one can design optical superlattices that posses photonic Dirac points (DPs) at frequencies at which the spatial average of the permittivity of the superlattice, $\bar{ \varepsilon}$, vanishes. Similar to the well-known zero-$\bar{n}$ bandgaps, we show that these zero-$\bar{\varepsilon}$ DPs are highly robust against structural disorder. We also show that, by tuning the graphene permittivity via the optical Kerr effect or electrical doping, one can induce a spectral variation of the DP exceeding \SI{30}{\nano\meter}, at mid-IR and THz frequencies. The implications of this wide tunability for the photonic Zitterbewegung effect in a vicinity of the DP are explored too.

Type: Article Optically and Electrically Tunable Dirac Points and Zitterbewegung in Graphene-Based Photonic Superlattices An open access version is available from UCL Discovery 10.1103/PhysRevB.91.201402 http://dx.doi.org/10.1103/PhysRevB.91.201402 English ©2015 American Physical Society. All rights reserved. Physical Review B ® is a trademark of the American Physical Society. Use of the American Physical Society websites and journals implies that the user has read and agrees to our Terms and Conditions and any applicable Subscription Agreement. physics.optics, physics.optics UCLUCL > Provost and Vice Provost Offices > UCL BEAMSUCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering ScienceUCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng https://discovery.ucl.ac.uk/id/eprint/1468425