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(96) Production(s) de FELBACQ D.
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Characterizing the Topological Properties of 1D Non‐Hermitian Systems without the Berry–Zak Phase
Auteur(s): Felbacq D., Rousseau E.
(Article) Publié:
Annalen Der Physik, vol. p. (2023)
Ref HAL: hal-04323455_v1
DOI: 10.1002/andp.202300321
Exporter : BibTex | endNote
Résumé: A new method is proposed to predict the topological properties of 1D periodic structures in wave physics, including quantum mechanics. From Bloch waves, a unique complex valued function is constructed, exhibiting poles and zeros. The sequence of poles and zeros of this function is a topological invariant that can be linked to the Berry–Zak phase. Since the characterization of the topological properties is done in the complex plane, it can easily be extended to the case of non‐Hermitian systems. The sequence of poles and zeros allows to predict topological phase transitions.
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Properties of dentin, enamel and their junction, studied with Brillouin scattering and compared to Raman microscopy
Auteur(s): Desoutter Alban, Felbacq D., Gergely C., Varga B., Bonnet L., Etienne P., Vialla R., Cuisinier Frédéric, Salehi Hamideh, Rousseau E., Ruffle B.
(Article) Publié:
Archives Of Oral Biology, vol. 152 p.105733 (2023)
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Detailed derivation of the generalized Snell–Descartes laws from Fermat’s principle
Auteur(s): Rousseau E., Felbacq D.
(Article) Publié:
Journal Of The Optical Society Of America A, vol. 40 p.676 (2023)
Texte intégral en Openaccess :
Ref HAL: hal-04073052_v1
DOI: 10.1364/JOSAA.478123
Exporter : BibTex | endNote
Résumé: Beginning with Fermat’s principle, we provide a detailed derivation of the generalized laws of refraction and reflection for a geometry realizing a metasurface. We first solve the Euler–Lagrange equations for a light ray propagating across the metasurface. The ray-path equation is found analytically, and the results are supported by numerical calculations. We get generalized laws of refraction and reflection that have three main features: (i) They are relevant in gradient-index optics and in geometrical optics; (ii) A collection of rays emerges from the metasurface as a result of multiple reflections inside the metasurface; and (iii) The laws, although derived from Fermat’s principle, differ from previously published results.
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Topological aspects of periodic and aperiodic photonic crystals
Auteur(s): Rousseau E., Kling Emmanuel, Felbacq D.
Conference: SPIE Nanoscience + Engineering (San Diego, FR, 2022-08-21)
Texte intégral en Openaccess :
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The Zak phase for lossy 1D photonic structures
Auteur(s): Felbacq D., Rousseau E., Kling Emmanuel
Conference: Active Photonic Platforms XIII (San Diego, FR, 2021-08-01)
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Multiobjective statistical learning optimization of RGB metalens
Auteur(s): Elsawy Mahmoud, Gourdin A., Binois Mickael, Duvigneau Régis, Felbacq D., Khadir Samira, Genevet Patrice, Lanteri Stéphane
(Article) Publié:
Acs Photonics, vol. 8 p.2498–2508 (2021)
Texte intégral en Openaccess :
Ref HAL: hal-03212349_v2
DOI: 10.1021/acsphotonics.1c00753
Exporter : BibTex | endNote
Résumé: Modelling of multi-wavelength metasurfaces relies on adjusting the phase of indi-vidual nanoresonators at several wavelengths.The traditional procedure neglects thenear-field coupling between the nanoresonators, which dramatically reduces the over-all diffraction efficiency, bandwidth, numerical aperture and device diameter.Anotheralternative design strategy is to combine a numerical optimization technique with full-wave simulations to mitigate this problem and optimize the entire metasurface at once.Here, we present a global multiobjective optimization technique that utilizes statisticallearning method to optimize RGB spherical metalenses at the visible wavelengths. Theoptimization procedure, coupled to a high-order full-wave solver, accounts for the nearfield coupling between the resonators. High numerical aperture RGB lenses(NA= 0.47and NA= 0.56) of 8μm and 10μm diameters are optimized with numerical average1focusing efficiencies of 55% and 45%, with an average focusing error smaller than 6%for the RGB colors. The fabricated and experimentally characterized devices present44.16% and 31.5% respective efficiencies. The reported performances represent thehighest focusing efficiencies for highNA >0.5 RGB metalenses obtained so far. Theintegration of multi-wavelength metasurfaces in portable and wearable electronic de-vices requires high performances to offer a variety of applications ranging from classicalimaging to virtual and augmented reality.
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Comment on the paper “Improving Poor Man’s Kramers-Kronig analysis and Kramers-Kronig constrained variational analysis”
Auteur(s): Rousseau E., Izard N., Bantignies J.-L., Felbacq D.
(Article) Publié:
-Spectrochimica Acta Part A Molecular And Biomolecular Spectroscopy [1994-...], vol. 259 p.119849 (2021)
Texte intégral en Openaccess :
Ref HAL: hal-03228703_v1
DOI: 10.1016/j.saa.2021.119849
Exporter : BibTex | endNote
Résumé: We clarify some analytical expressions existing in the literature, • Within the correct formulae we conclude that there is no need for an ad hoc improvement on the opposite to the title paper, • We highlight the symmetry properties of the function to be integrated in order to agree with the usual assumptions made to derive the Kramers-Kronig relations, • The analytical formula we provide may be used to increase the accuracy of the "Poor Man's Kramers-Kronig analysis" method and the "Kramers-Kronig constrained variational analysis" method.
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