arXiv subjects

Youssef El Badri

Publications and source records attributed to Youssef El Badri.

5 recordsLinked to original sources

arXiv2026

Material-Specific Mapping of Plasmonic Modal Dispersion via Discrete Momentum-Space Probes

Accurate measurement of surface plasmon polariton (SPP) dispersion remains challenging, as conventional angle-resolved techniques are limited by surface quality, diffraction artifacts, and geometry-induced band folding. Here, we show that SPP dispersion can be reconstructed from transmission spectra of plasmonic gratings with subwavelength apertures acting as Fabry-Pérot (FP) cavities. The approach harnesses modal hybridization between localized FP modes and SPPs, resolved using non-Hermitian eigenmode decomposition and validated by finite-difference time-domain simulations. ω-k dispersion mapping is achieved by varying the grating periodicity, with each structure probing a distinct in-plane momentum state. Geometry- and material-dependent corrections for aperture-induced leakage and dispersive phase shifts yield reconstructed relations in close agreement with eigenmode calculations across non-dispersive, Drude, and Drude-Lorentz models as well as experimental optical datasets spanning metals, oxides, and nitrides. The method is material-agnostic and requires no momentum-resolved instrumentation. Sensitivity to fabrication-induced wall roughness is also assessed: FP resonance positions remain spectrally stable with no measurable linewidth broadening across the explored perturbation range, and the modal field topology is largely preserved throughout. However, transmitted amplitude decreases monotonically owing to enhanced ohmic absorption at the perturbed boundaries.

physics.optics↗

arXiv2023

Symmetrical Anisotropy Enables Dynamic Diffraction Control in Photonics

Despite the steady advancements in nanofabrication made over the past decade that had prompted a plethora of intriguing applications across various fields, achieving compatibility between miniaturized photonic devices and electronic dimensions remains unachievable due to the inherent diffraction limit of photonic devices. Several approaches have emerged to overcome the diffraction restriction and leverage the spatial information carried by the evanescent waves. Negative dielectric permittivity materials can be utilized to build photonic crystals (PhCs) based on surface plasmon-polaritons. This approach, however, is known to be exceedingly dissipative, leading to significant optical losses for photonic components. Herein, we report an approach based on the anisotropic scaling of the shapes of PhCs to impede the diffraction barrier and enable a tunable diffraction limit. This approach opens up avenues for high-frequency wave guiding in cermet configuration, which was previously unachievable. Furthermore, asymmetric and symmetric dimer network-type PhCs were explored, with the asymmetric case demonstrating a quasi-bound state in the continuum with a quality factor of up to 41000.

physics.optics↗

arXiv2023

The emergence of low-frequency dual Fano resonances in chiral twisting metamaterials

In the current work, through a finite element analysis, we demonstrate that a configuration of chiral cells having syndiotactic symmetry provides dual Fano resonances at low frequency. From the phononic dispersion and transmission response, we compare the signature provided by a composite made of chiral cells to the ones of homogeneous medium, isotactic nonchiral, and isotactic chiral beams. The study results in an innovative design of a mechanical metamaterial that induces the Fano resonance at low frequency with a relatively high quality factor. This might be a significant step forward for mechanical wave filtering and detection. Performances have been evaluated using a sensor that will be implemented as a thermometer.

physics.app-ph↗

arXiv2022

Mapping of Elastic Properties of Twisting Metamaterials onto Micropolar Continuum using Static Calculations

Recent developments in the engineering of metamaterials have brought forth a myriad of mesmerizing mechanical properties that do not exist in ordinary solids. Among these, twisting metamaterials, acoustical chirality, or Willis coupling are sample-size dependent. The purpose of this work is, first, to examine the mechanical performance of a new twisting cubic metamaterial. Then, we perform a comparative investigation of its twisting behavior using the finite element method on microstructure elements computation, an analytical model, and we compare them to Eringen micropolar continuum. Notably, the results of the three models are in good qualitative and quantitative agreements. Finally, a systematic comparison of dispersion relations was made for the continuum and for the microstructures with different sizes in unit cells as final proof of perfect mapping.

physics.app-ph↗

arXiv2022

Longitudinal-Twist Wave Converter based on Chiral Metamaterials

Advances in material architectures have enabled endowing materials with exotic attributes not commonly available in the conventional realm of mechanical engineering. Twisting, a mechanism whereby metamaterials are used to transform static axial load into twist motion, is of particular interest to this study. Herein, computations based on the finite element method, corroborated by an analytical approach derived from applying Lagrange's equations to a monoatomic spring-mass system, are employed to explore the longitudinal-twist (L-T) conversion exhibited by a chiral tetragonal-beam metamaterial. Firstly, we perform an eigenvalue analysis taking into account the polarization states to highlight the potential contribution of the longitudinal mode in the L-T conversion. We contrast the twisting behavior of the chiral cell with that of other homogeneous medium, octagonal-tube, and non-chiral cells. Moreover, we demonstrate the influence of the cell's chirality on the L-T conversion using both time-domain and frequency-domain studies. The findings indicate that at least a portion of the longitudinally propagating wave is transformed into twist throughout a broad frequency range and even quasi-totally converted at distinct frequencies.

physics.app-ph↗