In the present article we numerically investigated the magneto-optical behaviour of a sub-wavelength structure composed by a monolayer graphene and a metallic metasurface of optical resonators. Using this hybrid graphene-metal structure, a large increase of the non-reciprocal polarization rotation of graphene can be achieved over a broad range of terahertz frequencies. We demonstrate that the symmetry of the resonator geometry plays a key role for the performance of the system: in particular, increasing the symmetry of the resonator the non-reciprocal properties can be progressively enhanced. Moreover, the possibility to exploit the metallic metasurface as a voltage gate to vary the graphene Fermi energy allows the system working point to be tuned to the desired frequency range. Another peculiar result is the achievement of a structure able to operate both in transmission and reflection with almost the same performance, but in a di erent frequency range of operation. The described system is hence a sub-wavelength, tunable, multifunctional, e ective non-reciprocal element in the terahertz region.

Symmetry enhanced non-reciprocal polarization rotation in a terahertz metal-graphene metasurface

Zanotto, Simone;Pitanti, Alessandro;Tredicucci, Alessandro
2018

Abstract

In the present article we numerically investigated the magneto-optical behaviour of a sub-wavelength structure composed by a monolayer graphene and a metallic metasurface of optical resonators. Using this hybrid graphene-metal structure, a large increase of the non-reciprocal polarization rotation of graphene can be achieved over a broad range of terahertz frequencies. We demonstrate that the symmetry of the resonator geometry plays a key role for the performance of the system: in particular, increasing the symmetry of the resonator the non-reciprocal properties can be progressively enhanced. Moreover, the possibility to exploit the metallic metasurface as a voltage gate to vary the graphene Fermi energy allows the system working point to be tuned to the desired frequency range. Another peculiar result is the achievement of a structure able to operate both in transmission and reflection with almost the same performance, but in a di erent frequency range of operation. The described system is hence a sub-wavelength, tunable, multifunctional, e ective non-reciprocal element in the terahertz region.
Settore FIS/03 - Fisica della Materia
Graphene; surface plasmons; metamaterials; Faraday rotation; terahertz
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11384/84506
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