Title: Pairing Toroidal and Magnetic Dipole Resonances in Elliptic Dielectric Rod Metasurfaces for Reconfigurable Wavefront Manipulation in Reflection

Abstract

Here, a novel approach for reconfigurable wavefront manipulation with gradient metasurfaces based on permittivity–modulated elliptic dielectric rods is proposed. It is shown that the required 2π phase span in the local electromagnetic response of the metasurface can be achieved by pairing the lowest magnetic dipole Mie resonance with a toroidal dipole Mie resonance, instead of using the lowest two Mie resonances corresponding to fundamental electric and magnetic dipole resonances as customarily exercised. This approach allows for the precise matching of both the resonance frequencies and quality factors. Moreover, the accurate matching is preserved if the rod permittivity is varied, allowing for constructing reconfigurable gradient metasurfaces by locally modulating the permittivity in each rod. Highly efficient tunable beam steering and beam focusing with ultrashort focal lengths are numerically demonstrated, highlighting the advantage of the low–profile metasurfaces over bulky conventional lenses. Notably, despite using a matched pair of Mie resonances, the presence of an electric polarizability background allows to perform the wavefront shaping operations in reflection, rather than transmission. This has the advantage that any control circuitry necessary in an experimental realization can be accommodated behind the metasurface without affecting the electromagnetic response.

Authors:

Tsilipakos, Odysseas  ^[1];

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Tasolamprou, Anna C. ^[1]; Koschny, Thomas ^[2]; Kafesaki, Maria ^[3]; Economou, Eleftherios N. ^[4]; Soukoulis, Costas M. ^[5]

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+ Show Author Affiliations

1. Institute of Electronic Structure and Laser FORTH GR‐71110 Heraklion Crete Greece
2. Ames Laboratory—U.S. DOE and Department of Physics and Astronomy Iowa State University Ames IA 50011 USA
3. Institute of Electronic Structure and Laser FORTH GR‐71110 Heraklion Crete Greece, Department of Materials Science and Technology University of Crete GR‐71003 Heraklion Crete Greece
4. Institute of Electronic Structure and Laser FORTH GR‐71110 Heraklion Crete Greece, Department of Physics University of Crete GR‐71003 Heraklion Crete Greece
5. Institute of Electronic Structure and Laser FORTH GR‐71110 Heraklion Crete Greece, Ames Laboratory—U.S. DOE and Department of Physics and Astronomy Iowa State University Ames IA 50011 USA

Publication Date:

2018-09-17

Research Org.:

Ames Lab., Ames, IA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1482749

Alternate Identifier(s):

OSTI ID: 1472158; OSTI ID: 1478228

Report Number(s):

IS-J-9789
Journal ID: ISSN 2195-1071

Grant/Contract Number:  

DE‐AC02‐07CH11358; 320081; 736876; AC02-07CH11358

Resource Type:

Published Article

Journal Name:

Advanced Optical Materials

Additional Journal Information:

Journal Name: Advanced Optical Materials Journal Volume: 6 Journal Issue: 22; Journal ID: ISSN 2195-1071

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

Germany

Language:

English

Subject:

36 MATERIALS SCIENCE; anomalous reflection; gradient metasurfaces; Mie resonances; toroidal dipole; tunable