Ref HAL: hal-01664518_v1
DOI: 10.1103/PhysRevA.96.062505
WoS: 000417919200004
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9 Citations
Résumé:

Based on the theory of macroscopic quantum electrodynamics, we generalize the expression of the Casimir force for nonreciprocal media. The essential ingredient of this result is the Green’s tensor between two nonreciprocal semi-infinite slabs, including a reflexion matrix with four coefficients that mixes optical polarizations. This Green’s tensor does not obey Lorentz’s reciprocity and thus violates time-reversal symmetry. The general result for the Casimir force is analyzed in the retarded and nonretarded limits, concentrating on the influences arising from reflections with or without change of polarization. In a second step, we apply our general result to a photonic topological insulator whose nonreciprocity stems from an anisotropic permittivity tensor, namely InSb. We show that there is a regime for the distance between the slabs where the magnitude of the Casimir force is tunable by an external magnetic field. Furthermore, the strength of this tuning depends on the orientation of the magnetic field with respect to the slab surfaces.

Ref HAL: hal-01624891_v1
DOI: 10.1103/PhysRevLett.119.173901
WoS: 000413770200001
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9 Citations
Résumé:

We show that the energy-transport efficiency in a chain of two-level emitters can be drastically enhanced by the presence of a photonic topological insulator (PTI). This is obtained by exploiting the peculiar properties of its nonreciprocal surface plasmon polariton (SPP), which is unidirectional, and immune to backscattering, and propagates in the bulk band gap. This amplification of transport efficiency can be as much as 2 orders of magnitude with respect to reciprocal SPPs. Moreover, we demonstrate that despite the presence of considerable imperfections at the interface of the PTI, the efficiency of the SPP-assisted energy transport is almost unaffected by discontinuities. We also show that the SPP properties allow energy transport over considerably much larger distances than in the reciprocal case, and we point out aparticularly simple way to tune the transport. Finally, we analyze the specific case of a two-emitter chain and unveil the origin of the efficiency amplification. The efficiency amplification and the practical advantages highlighted in this work might be particularly useful in the development of new devices intended to manage energy at the atomic scale.

Ref HAL: hal-01570566_v1
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We calculate the radiative heat transfer between two metallic gratings by exploiting the Adaptive Spatial Resolution metod. This technique dramatically improves the rate of convergence allowing to explore smaller separations. The heat flux shows a remarkable amplification of the exchanged energy, due to spoof-plasmon modes. We find a consistent disagreement with some previously obtained results going up to 50% (this disagreement is explained in terms of an incorrect connection between the reflection operators of the two gratings).

Ref HAL: hal-01570553_v1
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The Fourier Modal Method (FMM) is used to obtain the band structure of a 1D graphene based photonic crystal. The structure consists of graphene layers periodically inlayed in a homogeneous dielectric medium. In the model, the graphene sheet is considered as layer with atomic thickness. Under these conditions, we show that it is possible to use the FMM in order to obtain a polynomial eigenvalue problem allowing the computation of the band structure.

Ref HAL: hal-01570545_v1
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The Fourier Modal Method equipped with the concept of Adaptive Spatial Resolution (FMMASR) is derived and presented, in details, in the case of lamellar diffraction gratings under conical mounting. In the present work, we focus on efficiency and reduction of the numerical load.

Ref HAL: hal-01562609_v1
Ref Arxiv: 1702.02057
DOI: 10.1364/OE.25.014746
WoS: WOS:000404189800077
Ref. & Cit.: NASA ADS
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12 Citations
Résumé:

Radiative heat transfer between uniform plates is bounded by the narrow range and limited contribution of surface waves. Using a combination of analytical calculations and numerical gradient-based optimization, we show that such a limitation can be overcome in complicated multilayer geometries, allowing the scattering and coupling rates of slab resonances to be altered over a broad range of evanescent wavevectors. We conclude that while the radiative flux between two inhomogeneous slabs can only be weakly enhanced, the flux between a dipolar particle and an inhomogeneous slab—proportional to the local density of states—can be orders of magnitude larger, albeit at the expense of increased frequency selectivity. A brief discussion of hyperbolic metamaterials shows that they provide far less enhancement than optimized inho- mogeneous slabs.

Ref HAL: hal-01557223_v1
DOI: 10.1103/PhysRevB.96.045402
WoS: 000405026300018
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19 Citations
Résumé:

The radiative heat transfer between two dielectrics can be strongly enhanced in the near field in the presence of surface phonon-polariton resonances. Nevertheless, the spectral mismatch between the surface modes supported by two dissimilar materials is responsible for a dramatic reduction of the radiative heat flux they exchange. In the present paper we study how the presence of a graphene sheet, deposited on the material supporting the surfacewave of lowest frequency, allows us to widely tune the radiative heat transfer, producing an amplification factor going up to one order of magnitude. By analyzing the Landauer energy transmission coefficients we demonstratethat this amplification results from the interplay between the delocalized plasmon supported by graphene and the surface polaritons of the two dielectrics. We finally show that the effect we highlight is robust with respect to the frequency mismatch, paving the way to an active tuning and amplification of near-field radiative heat transfer in different configurations.