Plasmonics in a graphene cavity

The interaction between light and matter leads to a wide variety of polaritonic phenomena [1]. The confinement of these excitations in van der Waals heterostructures has allowed the direct imaging of surface plasmon polaritons (SPPs), and the effects of gating, sample boundaries and interfaces with different materials [2,3].

In this study, we investigate SPPs in graphene cavities. With a patterned graphite gate underneath the graphene, we can electrostatically define a cavity, and control the carrier density inside and outside the cavity. Lateral dimensions down to hundreds of nanometers are possible, comparable with the wavelength of the SPPs launched by the pn junctions bounding the cavity. We present the effects of confinement on the SPP dispersion, and its dependence on carrier densities on either side of the cavity edge.

References

[1] D.N. Basov, A. Asenjo-Garcia, P.J. Schuck, X.Y. Zhu, and Angel Rubio. Polaritons Panorama. Nanophotonics 10, 549 (2021).

[2] Y. Dong, L. Xiong, I. Y. Phinney et al. Fizeau drag in graphene plasmonics. Nature 594, 513–516 (2021).

[3] D. N. Basov, M. M. Fogler, and F. J. Garcia de Abajo. Polaritons in van der Waals materials. Science 354, 195 (2016).