// Place:

Instituto de Telecomunicações – Instituto Superior Técnico, Meeting Room – tbc

// Abstract:

Metasurfaces can be formed by structuring a plasmonic surface at the subwavelength scale and yield to richer interactions with external electromagnetic radiation than conventional gratings. In this talk I will discuss how conformal transformation can be used to design metasurfaces, focusing in the case where these transformations have singular points. This gives rise to singular metasurfaces which have continuous spectra rather than the discrete set of peaks characteristic of conventional gratings [1]. I will consider two instances of singular metasurfaces: (i) a metal surface with sharp edges [2] and (ii) a periodically doped graphene layer [3] whose conductivity minimum is smoothly suppressed. I will discuss the transition from a discrete to a continuous spectrum as the singular case is approached, and show how the singular graphene metasurface performs as a broadband THz absorber [4].

[1] J.B. Pendry, P.A. Huidobro, Y. Luo and E. Galiffi, “Compacted dimensions and singular plasmonic Metasurfaces”, Science, 358(6365), 915-917 (2017).

[2] F. Yang, P.A. Huidobro, J.B. Pendry, “A transformation optics approach to singular Metasurfaces”, Physical Review B 98 (12), 125409 (2018).

[3] P.A. Huidobro, M. Kraft, R. Kun, S.A. Maier and J.B. Pendry, “Graphene, plasmons and transformation optics”, Journal of Optics 18, 044024 (2016).

[4] E. Galiffi, J. B. Pendry and P.A. Huidobro, “Broadband THz absorption with singular graphene Metasurfaces”, ACS Nano, 12 (2), 1006-1013 (2018).