arXiv subjects

S. Guenneau

Publications and source records attributed to S. Guenneau.

18 recordsLinked to original sources

arXiv2025

W-shaped Broadband Attenuation of Longitudinal Waves through Composite Elastic Metamaterial

We investigate a composite elastic meta-slab with exceptional transmission properties, particularly the presence of a W-shaped bandgap. A comprehensive study, utilizing experimental measurements, the finite element method, and an analytical approach, identifies this specific bandgap. The meta-slab design involves cutting an array of composite materials arranged in parallel with strategically placed incisions. This configuration ensures that the materials between the slits act as plate-like waveguides within the surrounding medium. The incorporation of steel into ABS-based Fabry-Perot cavities induces a notable coupling effect between longitudinal waves and localized modes traversing the structure, leading to the formation of two distinct Fabry-Perot resonators. These coupling effects generate a series of resonances and antiresonances, ultimately producing the W-band gap through the interaction of two symmetric Fano resonances.

physics.optics↗

arXiv2023

Robust collimated beaming in 3D acoustic sonic crystals

We demonstrate strongly collimated beaming, at audible frequencies, in a three-dimensional acoustic phononic crystal where the wavelength is commensurate with the crystal elements; the crystal is a seemingly simple rectangular cuboid constructed from closely-spaced spheres, and yet demonstrates rich wave phenomena acting as a canonical three-dimensional metamaterial. We employ theory, numerical simulation and experiments to design and interpret this collimated beaming phenomenon and use a crystal consisting of a finite rectangular cuboid array of $4\times 10\times 10$ polymer spheres $1.38$~cm in diameter in air, arranged in a primitive cubic cell with the centre-to-centre spacing of the spheres, i.e. the pitch, as $1.5$~cm. Collimation effects are observed in the time domain for chirps with central frequencies at $14.2$~kHz and $18$~kHz, and we deployed a laser feedback interferometer or Self-Mixing Interferometer (SMI) -- a recently proposed technique to observe complex acoustic fields -- that enables experimental visualisation of the pressure field both within the crystal and outside of the crystal. Numerical exploration using a higher-order multi-scale finite element method designed for the rapid and detailed simulation of 3D wave physics further confirms these collimation effects and cross-validates with the experiments. Interpretation follows using High Frequency Homogenization and Bloch analysis whereby the different origin of the collimation at these two frequencies is revealed by markedly different isofrequency surfaces of the sonic crystal.

physics.app-ph↗

arXiv2022

Magneto-electric coupling and magnetism in photonic crystals: A high-order homogenization approach in the constitutive equations

We extend results of [Liu et al. Proc. Roy. Soc. Lond. A 469, 20130240, 2013] on artificial magneto-electric coupling and magnetism in moderate contrast dielectric layered media via high-order homogenization to the three-dimensional setting. For this, we consider asymptotic expansions in the vector Maxwell system. We then illustrate effect of magneto-electric coupling with numerical simulations for a layered system alternating positively and negatively refracting index. We unveil hyperbolic behaviour and magneto-electric coupling and derive a sharper estimate for the anisotropic effective medium in [Ramakrishna et al., J. Mod. Optics, 50, 1419-1430, 2003]. We also revisit the effective medium description of a PT-symmetric layered structure in [Novitsky, Shalin, Novitsky, Phys. Rev. A 99, 043812, 2019], adding higher-order approximation orders.

physics.optics↗

arXiv2021

Cloaking strategy for Love waves

Love waves are antiplane elastic waves which propagate along the surface of a heterogeneous medium. Under time-harmonic regime, they are governed by a scalar equation of the Helmholtz type. We exploit the invariance of this governing equation under an in-plane arbitrary coordinate transformation to design broadband cloaks for surface defects. In particular, we apply transformation elastodynamics to determine the anisotropic, position dependent, mechanical properties of ideal cloaks able to hide triangular and parabolic-shaped defects. Dispersion analysis and time-harmonic numerical simulations are employed to validate the proposed strategy. Next, we utilize layered monoclinic materials, with homogenized properties matching those of ideal cloaks, to design feasible cloaks. The performance of the layered cloaks is validated via time-harmonic numerical simulations which show a significant reduction of the defect-generated scattered fields.

physics.app-ph↗

arXiv2020

CPA-Lasing in Thin-Elastic Plates via Exceptional Points

We present here how a coherent perfect absorber-laser (CPAL) enabled by parity-time ($\mathcal{PT}$)-symmetry breaking may be exploited to build monochromatic amplifying devices for flexural waves. The fourth order partial differential equation governing the propagation of flexural waves leads to four by four transfer matrices, and this results in physical properties of the $\mathcal{PT}$-symmetry specific to elastic plate systems. We thus demonstrate the possibility of using CPAL for such systems and we argue the possibility of using this concept to detect extremely small-scale vibration perturbations with important outcomes in surface science (imaging of nanometer vibration) and geophysics (improving seismic sensors like velocimeters). The device can also generate finite signals using very low exciting intensities. The system can alternatively be used as a perfect absorber for flexural energy by tailoring the left and right incident wave for energy harvesting applications.

physics.class-ph↗

arXiv2019

Fresnel drag in space-time modulated metamaterials

A moving medium drags light along with it as measured by Fizeau and explained by Einstein's theory of special relativity. Here we show that the same effect can be obtained in a situation where there is no physical motion of the medium. Modulations of both the permittivity and permeability, phased in space and time in the form of travelling waves, are the basis of our model. Space-time metamaterials are represented by effective bianisotropic parameters, which can in turn be mapped to a moving homogeneous medium. Hence these metamaterials mimic a relativistic effect without the need for any actual material motion. We discuss how both the permittivity and permeability need to be modulated in order to achieve these effects, and we present an equivalent transmission line model.

physics.optics↗

arXiv2018

Scattering Cancellation based Cloaking for the Maxwell-Cattaneo Heat Waves

In this work we theoretically propose scattering cancellation-based cloaks for heat waves that obey the Maxwell-Cattaneo equation. The proposed cloaks possess carefully tailored diffusivity to cancel the dipole scattering from the object that they surround, and thus can render a small object invisible in the near and far fields, as demonstrated by full-wave finite-element simulations. Mantle heat cloaking is further analyzed and proposed to simplify the design and bring this cloaking technology one step closer to its practical implementation, with promising applications in nanoelectronics and defense related applications.

physics.optics↗

arXiv2018

Acoustic flat lensing using an indefinite medium

Acoustic flat lensing is achieved here by tuning a phononic array to have indefinite medium behaviour in a narrow frequency spectral region along the acoustic branch. This is confirmed by the occurrence of a flat band along an unusual path in the Brillouin zone and by interpreting the intersection point of isofrequency contours on the corresponding isofrequency surface; coherent directive beams are formed whose reflection from the array surfaces create lensing. Theoretical predictions are corroborated by time-domain experiments, airborne acoustic waves generated by a source with a frequency centered about $10.6$ kHz, placed at three different distances from one side of a finite phononic crystal slab, constructed from polymeric spheres, yield distinctive focal spots on the other side. These experiments evaluate the pressure field using optical feedback interferometry and demonstrate precise control of the three-dimensional wave trajectory through a sonic crystal.

physics.class-ph↗

arXiv2017

Clamped seismic metamaterials: Ultra-low broad frequency stop-bands

The regularity of earthquakes, their destructive power, and the nuisance of ground vibration in urban environments, all motivate designs of defence structures to lessen the impact of seismic and ground vibration waves on buildings. Low frequency waves, in the range $1$ to $10$ Hz for earthquakes and up to a few tens of Hz for vibrations generated by human activities, cause a large amount of damage, or inconvenience, depending on the geological conditions they can travel considerable distances and may match the resonant fundamental frequency of buildings. The ultimate aim of any seismic metamaterial, or any other seismic shield, is to protect over this entire range of frequencies, the long wavelengths involved, and low frequency, have meant this has been unachievable to date. Elastic flexural waves, applicable in the mechanical vibrations of thin elastic plates, can be designed to have a broad zero-frequency stop-band using a periodic array of very small clamped circles. Inspired by this experimental and theoretical observation, all be it in a situation far removed from seismic waves, we demonstrate that it is possible to achieve elastic surface (Rayleigh) and body (pressure P and shear S) wave reflectors at very large wavelengths in structured soils modelled as a fully elastic layer periodically clamped to bedrock. We identify zero frequency stop-bands that only exist in the limit of columns of concrete clamped at their base to the bedrock. In a realistic configuration of a sedimentary basin 15 meters deep we observe a zero frequency stop-band covering a broad frequency range of $0$ to $30$ Hz.

physics.class-ph↗

arXiv2016

Flexural Mie Resonances: Localized Surface Platonic Modes

Surface plasmons polaritons were thought to exist only in metals near their plasma frequencies. The concept of spoof plasmons extended the realms of plasmonics to domains such as radio frequencies, magnetism, or even acoustic waves. Here, we introduce the concept of localized surface platonic modes (SPMs). We demonstrate that they can be generated on a two-dimensional clamped (or stress-free) cylindrical surface, in a thin elastic plate, with subwavelength corrugations under excitation by an incident flexural plane wave. Our results show that the corrugated rigid surface is elastically equivalent to a cylindrical scatterer with negatively uniform and dispersive flexural rigidity. This, indeed, suggests that plasmonic-like platonic materials can be engineered with potential applications in various areas including earthquake sensing, or elastic imaging and cloaking.

physics.class-ph↗

arXiv2016

Analysis in temporal regime of dispersive invisible structures designed from transformation optics

A simple invisible structure made of two anisotropic homogeneous layers is analyzed theoretically in temporal regime. The frequency dispersion is introduced and analytic expression of the transient part of the field is derived for large times when the structure is illuminated by a causal excitation. This expression shows that the limiting amplitude principle applies with transient fields decaying as the power -3/4 of the time. The quality of the cloak is then reduced at short times and remains preserved at large times. The one-dimensional theoretical analysis is supplemented with full-wave numerical simulations in two-dimensional situations which confirm the effect of dispersion.

physics.optics↗

arXiv2015

Modulation of diffusion rate of therapeutic peptide drugs using graphene oxide membranes

We investigate diffusion of a peptide drug through Graphene Oxide (GO) membranes that are modeled as a porous layered laminate constructed from aligned flakes of GO. Our experiments using a peptide drug show a tunable non-linear dependence of the peptide concentration upon time. This is confirmed using numerical simulations with a diffusion equation accounting for the photothermal degradation of fluorophores and an effective percolation model. This modeling yields an interpretation of the control and delay of drug diffusion through GO membranes. The ability to modulate the density of hydrogel-like GO membranes to control drug release rates could be a step forwards in tailoring drug release properties of the hydrogels for therapeutic applications.

cond-mat.mtrl-sci↗

arXiv2015

Transformation seismology: composite soil lenses for steering surface elastic Rayleigh waves

Metamaterials are artificially structured media that can focus (lensing) or reroute (cloaking) waves, and typically this is developed for electromagnetic waves at millimetric down to nanometric scales or for acoustics or thin elastic plates at centimeter scales. Extending the concepts of Kadic et al. 2013 we show that the underlying ideas are generic across wave systems and scales by generalizing these concepts to seismic waves at frequencies, and lengthscales of the order of hundreds of meters, relevant to civil engineering. By applying ideas from transformation optics we can manipulate and steer Rayleigh surface wave solutions of the vector Navier equations of elastodynamics; this is unexpected as this vector system is, unlike Maxwell's electromagnetic equations, not form invariant under transformations. As a paradigm of the conformal geophysics that we are creating, we design a square arrangement of Luneburg lenses to reroute and then refocus Rayleigh waves around a building with the dual aim of protection and minimizing the effect on the wavefront (cloaking) after exiting the lenses. To show that this is practically realisable we deliberately choose to use material parameters readily available and this metalens consists of a composite soil structured with buried pillars made of softer material. The regular lattice of inclusions is homogenized to give an effective material with a radially varying velocity profile that can be directly interpreted as a lens refractive index. We develop the theory and then use full 3D time domain numerical simulations to conclusively demonstrate the validity of the transformation seismology ideas: we demonstrate, at frequencies of seismological relevance 3-10 Hz, and for low speed sedimentary soil ($v_s$: 300-500 m/s), that the vibration of a structure is reduced by up to 6 dB at its resonance frequency.

cond-mat.mtrl-sci↗

arXiv2015

Spectral analysis of one-dimensional high-contrast elliptic problems with periodic coefficients

We study the behaviour of the spectrum of a family of one-dimensional operators with periodic high-contrast coefficients as the period goes to zero, which may represent e.g. the elastic or electromagnetic response of a two-component composite medium. Compared to the standard operators with moderate contrast, they exhibit a number of new effects due to the underlying non-uniform ellipticity of the family. The effective behaviour of such media in the vanishing period limit also differs notably from that of multi-dimensional models investigated thus far by other authors, due to the fact that neither component of the composite forms a connected set. We then discuss a modified problem, where the equation coefficient is set to a positive constant on an interval that is independent of the period. Formal asymptotic analysis and numerical tests with finite elements suggest the existence of localised eigenfunctions ("defect modes"), whose eigenvalues situated in the gaps of the limit spectrum for the unperturbed problem.

math.AP↗

arXiv2014

Biharmonic Split Ring Resonator Metamaterial: Artificially dispersive effective density in thin periodically perforated plates

We present in this paper a theoretical and numerical analysis of bending waves localized on the boundary of a platonic crystal whose building blocks are split ring resonators (SRR). We first derive the homogenized parameters of the structured plate using a three-scale asymptotic expansion in the linearized biharmonic equation. In the limit when the wavelength of the bending wave is much larger than the typical heterogeneity size of the platonic crystal, we show that it behaves as an artificial plate with an anisotropic effective Young modulus and a dispersive effective mass density. We then analyze dispersion diagrams associated with bending waves propagating within an infinite array of SRR, for which eigen-solutions are sought in the form of Floquet-Bloch waves. We finally demonstrate that this structure displays the hallmarks of All-Angle-Negative-Refraction(AANR) and it leads to superlensing and ultrarefraction effects, interpreted thanks to our homogenization model as a consequence of negative and vanishing effective density, respectively.

cond-mat.mtrl-sci↗

arXiv2014

Time Driven Subwavelength Focusing with Negative Refraction

Flat lens concept based on negative refraction proposed by Veselago in 1968 has been mostly investigated in monochromatic regime. It was recently recognized that time development of the super-lensing effect discovered in 2000 by Pendry is yet to be assessed and may spring surprises: Time-dependent illumination could improve the spatial resolution of the focusing. We investigate dynamics of flexural wave focusing by a 45\degre-tilted square lattice of circular holes drilled in a Duraluminium plate. Time-resolved experiments reveal that the focused image shrinks with time below diffraction limit, with a lateral resolution increasing from 0.8 $λ$ to 0.35 $λ$, whereas focusing under harmonic excitation remains diffraction limited. Modal analysis reveals the role in pulse reconstruction of radiating lens resonances, which repeatedly self-synchronize at the focal spot to shape a super-oscillating field.

cond-mat.mtrl-sci↗

arXiv2013

Photonic crystal carpet: Manipulating wave fronts in the near field at 1550 nm

Ground-plane cloaks, which transform a curved mirror into a flat one, and recently reported at wavelengths ranging from the optical to the visible spectrum, bring the realm of optical illusion a step closer to reality. However, all carpet-cloaking experiments have thus far been carried out in the far-field. Here, we demonstrate numerically and experimentally that a dielectric photonic crystal (PC) of a complex shape made of a honeycomb array of air holes can scatter waves in the near field like a PC with a at boundary at stop band frequencies. This mirage effect relies upon a specific arrangement of dielectric pillars placed at the nodes of a quasi-conformal grid dressing the PC. Our carpet is shown to work throughout the range of wavelengths 1500nm to 1650nm within the stop band extending from 1280 to 1940 nm. The device has been fabricated using a single- mask advanced nanoelectronics technique on III-V semiconductors and the near field measurements have been carried out in order to image the wave fronts's curvatures around the telecommunication wavelength 1550 nm.

physics.optics↗

arXiv2010

Non-singular arbitrary cloaks dressing three-dimensional anisotropic obstacles

We design three dimensional electromagnetic cloaks, starting from a small region of complex shape instead of a point. We derive the expression of a transformation matrix describing an objet with a surface of revolution and its associated non-singular cloak. We note that while none of the eigenvalues vanish inside the cloak, they suffer a discontinuity on its inner surface. Moreover, all three eigenvalues are independent upon the radius in the concealed object. The validity of our analytical results is confirmed by finite edge-elements computations showing scattering is much reduced when the object is dressed with the cloak. We note that neither the object nor the cloak are invisible on their own.

physics.comp-ph↗