arXiv subjects

Mathieu Mivelle

Publications and source records attributed to Mathieu Mivelle.

At least 19 recordsLinked to original sources

arXiv2026

Optical Magnetic-Field Gating of Photon Avalanching Quantum Processes

Highly nonlinear phenomena, where macroscopic changes are triggered by microscopic perturbations, are ubiquitous in complex systems ranging from epidemic spreading to neural networks. In optics, photon avalanching represents a prime manifestation of such highly nonlinear behavior, characterized by a steep nonlinear response (s) following an avalanche threshold. However, this nonlinearity is typically determined by material composition, making this behavior challenging to tune for adaptive sensing, imaging, and neuromorphic applications. Here, we demonstrate giant optical magnetic field gated threshold and nonlinearity in lanthanide doped nanoparticles. We exploit the distinct quantum selection rules of the avalanche process: while the energy looping cycles of excited state absorption and cross relaxation are primarily electrically driven, the seed excitation, ground state absorption, is a mixed transition permitting magnetic dipole interaction. By positioning the emitters within an optical standing wave to spatially partition the electromagnetic field, we tune the local magnetic to electric field balance to selectively regulate the seeding and amplification probabilities. This allows us to demonstrate an unprecedented dynamic range of control over the power threshold and nonlinearity, tuning the order from s = 15 to s = 62. Furthermore, we harness this spatial separation of electric and magnetic fields using tightly focused cylindrical vector beams to locally sculpt the nonlinearity of a single nanocluster, achieving sub wavelength super resolution imaging that substantially surpasses conventional photon avalanche imaging under Gaussian illumination. These findings establish the magnetic component of light as a practical knob to actively program nonlinear optical dynamics, sub diffraction nanoscopy, and critical quantum dynamics at the nanoscale.

physics.optics↗

arXiv2026

Plasmonic Metasurfaces for Magnetic Skyrmion Control via the Inverse Faraday Effect

Magnetic skyrmions hold high promise for low power spintronic and neuromorphic computing. However, existing manipulation schemes rely predominantly on local thermal excitation, rendering nucleation stochastic and lacking a non-destructive mechanism for targeted erasure. Here, we demonstrate a deterministic, optomagnetic field-driven paradigm for fast, all-optical writing and erasing of magnetic skyrmion crystals using a magneto-plasmonic metasurface. By tailoring surface lattice resonances in a periodic nanodisk array, circularly polarized light excites giant super-circular optical spin densities that drive intense circulating drift photocurrents via the inverse Faraday effect. This delivers synchronized picosecond magnetic field pulses into an adjacent magnetic multilayer. Micromagnetic simulations reveal that a single optical pulse deterministically nucleates stable Néel skyrmions through a transient Bloch to Néel relaxation pathway governed by optical helicity and interfacial Dzyaloshinskii Moriya interaction. Crucially, reversing incident light helicity allows on-demand topological reconfiguration: under a confining bias field, the inverted optomagnetic field unwinds pre existing skyrmions to restore a uniform ground state. Furthermore, we demonstrate the targeted writing of stable skyrmionium states. By bypassing stochastic thermal cycles and achieving reversible topological control on picosecond timescales, this work bridges nanophotonics, plasmonics, and magnetism, establishing a scalable foundation for high-speed, reconfigurable information processing and unconventional computing.

physics.optics↗

arXiv2026

Synthesis of hybrid gold-protein nanobioconjugates with strongly enhanced circular dichroism

Controlling chiral light-matter interactions with nanophotonics is a powerful strategy for amplifying molecular circular dichroism (CD) beyond its natural limits. Here, we present a plasmonic platform that uses superchiral near fields to amplify the optical activity of biological chromophores. Gold nanoparticles (3.6 nm in diameter) are electrostatically coupled with photosynthetic proteins which results in stable hybrid nanobioconjugates in aqueous solution. The Q-band absorption spectrum of the proteins overlaps with the localized surface plasmon resonance of the gold particles. In the visible region, a combination of numerical simulations and normalized CD measurements reveal an enhancement factor of 3 compared to free proteins. This observation reveals three effects. First, there is a local increase in electromagnetic chirality density in the protein environment. Second, there is an increase in the absorption of the proteins. Third, there is plasmon-induced circular dichroism. Our results quantitatively demonstrate that near-field super-chirality directly modulates biomolecular optical activity. These findings open new avenues for chiroptical nanodevices, biosensing platforms, and light-driven asymmetric photochemistry.

physics.optics↗

arXiv2026

Symmetry-Engineered Magnetic Dipole Emission in Plasmonic Core-Satellite Resonators

Magnetic dipole (MD) transitions are intrinsically weak and highly sensitive to emitter orientation and position, making their controlled enhancement at optical frequencies particularly challenging. Here we show that structural symmetry provides a powerful route to robust magnetic light-matter interactions. We systematically investigate plasmonic core-satellite resonators composed of N metallic nanoparticles arranged on a dielectric core. We evaluate their performance using a unified figure of merit that accounts for magnetic Purcell enhancement, electric dipole suppression, quantum efficiency, and robustness to emitter orientation and fabrication tolerances. We find that the optimal structures correspond to the highest-symmetry geometries, which naturally produce spatially homogeneous and orientation-independent magnetic Purcell enhancement. In particular, the dodecapod configuration yields strong magnetic emission with Purcell factors approaching 250, high radiative efficiency, and suppressed electric dipole contributions. Quasinormal-mode and complex mode-volume analysis reveal that symmetry enforces uniform magnetic modal confinement within the core, explaining both the enhancement and its robustness. These results establish symmetry as a guiding principle for designing nanophotonic resonators with controlled multipolar light-matter interactions and provide a practical route toward bright and selective magnetic dipole emitters.

physics.optics↗

arXiv2025

All-optical directional switching of non-thermal photocurrents in plasmonic nanocircuits

Controlling the flow of electricity in metallic circuits with light is a key goal for future optoelectronics. In this work, we demonstrate all-optical generation and directional control of non-thermal drift photocurrents in a plasmonic gold wire. We attribute this phenomenon to the Inverse Faraday Effect and show that the current's direction can be precisely reversed at a subwavelength scale by tailoring the incident light's polarization or laser beam position. A bespoke polarization modulation technique is employed to unambiguously separate ultrafast drift currents from the ubiquitous photothermal background. We further reveal a collaborative mechanism where macroscopic thermal gradients, acting as a driving force, are used to extract and remotely detect the locally-generated nanoscale photocurrents. This robust control and detection scheme paves the way for reconfigurable, all-optical nanocircuitry capable of ultrafast on-chip processing.

physics.optics↗

arXiv2025

Engineering Magnetization with Photons: Nanoscale Advances in the Inverse Faraday Effect for Metallic and Plasmonic Systems

The inverse Faraday effect, the ability of light to act as a source of magnetism, is a cornerstone of modern ultrafast optics. Harnessing this effect at the nanoscale promises to transform data storage and spintronics, yet its predictive understanding remains elusive. This review synthesizes recent progress in engineering the IFE within plasmonic architectures. We bridge the theoretical foundations, from classical drift current models to quantum descriptions, with the latest experimental milestones, including pump probe studies that have verified the effect s subpicosecond nature. Special emphasis is placed on how nanostructure design allows for unprecedented control, enabling functionalities like chiral or reversed magnetization by locally sculpting the optical spin density. Despite this progress, a crucial challenge pervades the field, a stark, often orders of magnitude, mismatch between predicted and measured magnetization values. We contend that resolving this discrepancy is paramount. The path forward requires the development of novel experimental probes capable of directly imaging these fleeting magnetic fields at their native length and time scales, ultimately unlocking the true potential of nanoscale optical magnetism.

physics.optics↗

arXiv2025

Twisting Light, Steering Spins: Gold Nanoparticle Magnetization via Inverse Faraday and Orbital Angular Momentum

We present a new approach to controlling magnetization in gold nanoparticles using the Inverse Faraday Effect combined with Laguerre-Gauss beams carrying orbital angular momentum. By tailoring the tilt of isophase planes, we induce drift photocurrents that generate magnetic fields tilted by up to 25° relative to the beam axis. The magnetic orientation can be reversed by switching polarization chirality or the orbital angular momentum sign, and it can be rotated azimuthally by repositioning the particle, accessing any angle over 2π steradians. This unprecedented level of control extends all-optical magnetization to three-dimensional orientations, potentially at ultrafast timescales given the near-instantaneous nature of the Inverse Faraday Effect. Our results pave the way for advanced spin-based applications, from triggering spin waves in magnetic materials to designing next-generation magnetic memory and logic devices.

physics.optics↗

arXiv2024

Skyrmion Generation in a Plasmonic Nanoantenna through the Inverse Faraday Effect

Skyrmions are topological structures characterized by a winding vectorial configuration that provides a quantized topological charge. In magnetic materials, skyrmions are localized spin textures that exhibit unique stability and mobility properties, making them highly relevant to the burgeoning field of spintronics. In optics, these structures open new frontiers in manipulating and controlling light at the nanoscale. The convergence of optics and magnetics holds therefore immense potential for manipulating magnetic processes at ultrafast timescales. Here, we explore the possibility of generating skyrmionic topological structures within the magnetic field induced by the inverse Faraday effect in a plasmonic nanostructure. Our investigation reveals that a gold nanoring, featuring a dark mode, can generate counter-propagating photocurrents between its inner and outer segments, thereby enabling the magnetization of gold and supporting a skyrmionic vectorial distribution. We elucidate that these photocurrents arise from the localized control of light polarization, facilitating their counter-propagative motion. The generation of skyrmions through the inverse Faraday effect at the nanoscale presents a pathway towards directly integrating this topology into magnetic layers. This advancement holds promise for ultrafast timescales, offering direct applications in ultrafast data writing and processing.

physics.optics↗

arXiv2024

Femtosecond drift photocurrents generated by an inversely designed plasmonic antenna

Photocurrents play a crucial role in various applications, including light detection, photovoltaics, and THz radiation generation. Despite the abundance of methods and materials for converting light into electrical signals, the use of metals in this context has been relatively limited. Nanostructures supporting surface plasmons in metals offer precise light manipulation and induce light-driven electron motion. Through inverse design optimization of a gold nanostructure, we demonstrate enhanced volumetric, unidirectional, intense, and ultrafast photocurrents via a magneto-optical process derived from the inverse Faraday effect. This is achieved through fine-tuning the amplitude, polarization, and their gradients in the local light field. The virtually instantaneous process allows dynamic photocurrent modulation by varying optical pulse duration, potentially yielding nanosources of intense, ultrafast, planar magnetic fields, and frequency-tunable THz emission. These findings opens avenues for ultrafast magnetic material manipulation and holds promise for nanoscale THz spectroscopy.

physics.optics↗

arXiv2024

Nanoscale Control over Magnetic Light-Matter Interactions

Light-matter interactions are frequently perceived as predominantly influenced by the electric optical field, with the magnetic component of light often overlooked. Nonetheless, the magnetic aspect plays a pivotal role in various optical processes, including chiral light-matter interactions, photon-avalanching, and forbidden photochemistry, underscoring the significance of manipulating magnetic processes in optical phenomena. Here, we explore the ability to control the magnetic light and matter interactions at the nanoscale. In particular, we demonstrate experimentally, using a plasmonic nanostructure, the transfer of energy from the optical magnetic field to a nanoparticle, thanks to the deep subwavelength magnetic confinement allowed by our nano-antenna. This control is made possible by the particular design of our plasmonic nanostructure, which has been optimized to spatially separate the electric and magnetic fields of the localized plasmon. Furthermore, by studying the spontaneous emission from the Lanthanide-ions doped nanoparticle, we observe that the optical field distributions are not spatially correlated with the electric and magnetic near-field quantum environments of this antenna, which seemingly contradicts the reciprocity theorem. We demonstrate that this counter-intuitive observation is in fact, the result of the different optical paths followed by the excitation and emission of the ions, which forbids a direct application of that theorem.

physics.optics↗

arXiv2023

A Reversed Inverse Faraday Effect

The inverse Faraday effect is a magneto-optical process allowing the magnetization of matter by an optical excitation carrying a non-zero spin of light. In particular, a right circular polarization generates a magnetization in the direction of light propagation and a left circular polarization in the opposite direction to this propagation. We demonstrate here that by manipulating the spin density of light, i.e., its polarization, in a plasmonic nanostructure, we generate a reversed inverse Faraday effect. A right circular polarization will generate a magnetization in the opposite direction of the light propagation, a left circular polarization in the direction of propagation. Also, we demonstrate that this new physical phenomenon is chiral, generating a strong magnetic field only for one helicity of the light, the opposite helicity producing this effect only for the mirror structure. This new optical concept opens the way to the generation of magnetic fields with unpolarized light, finding application in the ultrafast manipulation of magnetic domains and processes, such as spin precession, spin currents, and waves, magnetic skyrmion or magnetic circular dichroism, with direct applications in data storage and processing technologies.

physics.optics↗

arXiv2023

A magnetic monopole nanoantenna

Magnetic monopoles are hypothetical particles that, like electric monopoles which generate electric fields, are at the origin of magnetic fields. Despite many efforts, to date, these theoretical particles have yet to be observed. Nevertheless, many systems or physical phenomena can be related to magnetic monopole behavior. Here, we propose a new type of photonic nanoantenna behaving as a radiating magnetic monopole. We demonstrate that a half-nanoslit in a semi-infinite gold layer generates a single pole of an enhanced magnetic field at the nanoscale and that this single pole radiates efficiently in the far field. This original antenna concept opens the way to a new model system to study magnetic monopoles, to a new source of optical magnetic field to study the "magnetic light" and matter coupling, and allows potential applications at other frequencies such as magnetic resonance imaging.

physics.optics↗

arXiv2023

An achiral magnetic photonic antenna as a tunable nanosource of superchiral light

Sensitivity to molecular chirality is crucial for many fields, from biology and chemistry to the pharmaceutical industry. By generating superchiral light, nanophotonics has brought innovative solutions to reduce the detection volume and increase sensitivity at the cost of a non-selectivity of light chirality or a strong contribution to the background. Here, we theoretically propose an achiral plasmonic resonator, based on a rectangular nanoslit in a thin gold layer behaving as a magnetic dipole, to generate a tunable nanosource of purely superchiral light. This nanosource is free of any background, and the sign of its chirality is externally tunable in wavelength and polarization. These properties result from the coupling between the incident wave and the magnetic dipolar character of our nano-antenna. Thus, our results propose a platform with deep subwavelength detection volumes for chiral molecules in particular, in the visible, and a roadmap for optimizing the signal-to-noise ratios in circular dichroism measurements to reach single-molecule sensitivity.

physics.optics↗

arXiv2023

Broadband plasmonic nanoantennas for multi-color nanoscale dynamics in living cells

Recently, the implementation of plasmonic nanoantennas has opened new possibilities to investigate the nanoscale dynamics of individual biomolecules in living cell. However, studies have yet been restricted to single molecular species as the narrow wavelength resonance of gold-based nanostructures precludes the simultaneous interrogation of different fluorescently labeled molecules. Here we exploited broadband aluminum-based nanoantennas carved at the apex of near-field probes to resolve nanoscale-dynamic molecular interactions on intact living cell membranes. Through multicolor excitation, we simultaneously recorded fluorescence fluctuations of dual-color labeled transmembrane receptors known to form nanoclusters in living cells. Fluorescence cross-correlation studies revealed transient interactions between individual receptors in regions of ~60 nm. Moreover, the high signal-to-background ratio provided by the antenna illumination allowed us to directly detect fluorescent bursts arising from the passage of individual receptors underneath the antenna. Remarkably, by reducing the illumination volume below the characteristic receptor nanocluster sizes, we resolved molecular diffusion within nanoclusters and distinguished it from nanocluster diffusion. Spatiotemporal characterization of transient interactions between molecules is crucial to understand how they communicate with each other to regulate cell function. Our work demonstrates the potential of broadband photonic antennas to study multi-molecular events and interactions in living cell membranes with unprecedented spatiotemporal resolution.

physics.optics↗

arXiv2023

Full control of electric and magnetic light-matter interactions through a plasmonic nanomirror on a near-field tip

Light-matter interactions are often considered governed by the electric optical field only, leaving aside the magnetic component of light. However, the magnetic part plays a determining role in many optical processes from light and chiral-matter interactions, photon-avalanching to forbidden photochemistry, making the manipulation of magnetic processes extremely relevant. Here, by creating a standing wave using a plasmonic nanomirror we manipulate the spatial distributions of the electric and magnetic fields and their associated local density of states, allowing the selective control of the excitation and emission of electric and magnetic dipolar transitions. This control allows us to image, in 3D, the electric and magnetic nodes and anti-nodes of the fields interference pattern. It also enables us to enhance specifically photoluminescence from quantum emitters excited only by the magnetic field, and to manipulate their quantum environment by acting on the excitation fields solely, demonstrating full control of magnetic and electric light-matter interactions.

physics.optics↗

arXiv2023

A Chiral Inverse Faraday Effect Mediated by an Inversely Designed Plasmonic Antenna

The inverse Faraday effect is a magneto-optical process allowing the magnetization of matter by an optical excitation carrying a non-zero spin or orbital moment of light. This phenomenon was considered until now as symmetric; right or left circular polarizations generate magnetic fields oriented in the direction of light propagation or in the counter-propagating direction. Here, we demonstrate that by manipulating the spin density of light in a plasmonic nanostructure, we generate a chiral inverse Faraday effect, creating a strong magnetic field of 500 mT only for one helicity of the light, the opposite helicity producing this effect only for the mirror structure. This new optical concept opens the way to the generation of magnetic fields with unpolarized light, finding application in the ultrafast manipulation of magnetic domains and processes, such as spin precession, spin currents and waves, magnetic skyrmion or magnetic circular dichroism, with direct applications in data storage and data processing technologies.

physics.optics↗

arXiv2022

An inverse Faraday effect through linear polarized light

The inverse Faraday effect (IFE) allows the generation of magnetic fields by optical excitation only. Since its discovery in the 60s, it was believed that only an elliptical or circular polarization could magnetize matter by this magneto-optical phenomenon. Here, we demonstrate the generation of an IFE via a linear polarization of light. This new physical concept results from the local manipulation of light by a plasmonic nano-antenna. We demonstrate that a gold nanorod excited by a linear polarization generates a non-zero magnetic field by IFE when the incident polarization of the light is not parallel to the long axis of the rod. We show that this dissymmetry generates hot spots of local non-vanishing spin densities (local elliptical polarization state), introducing the concept of super circular light, allowing this magnetization. Moreover, by varying the angle of the incident linear polarization with respect to the nano-antenna, we demonstrate the on-demand flipping of the magnetic field orientation. Finally, this linear IFE generates a stationary magnetic field 25 times stronger than what a gold nanoparticle produces when excited by a circular polarization and via a classical IFE. The creation of stationary magnetic fields by IFE in a plasmonic nanostructure is nowadays the only technique allowing the creation of ultra-short, intense magnetic field pulses at the nanoscale. Thus, it finds applications in the ultrafast control of magnetic domains with applications not only in data storage technologies but also in research fields such as magnetic trapping, magnetic skyrmion, magnetic circular dichroism, to spin control, spin precession, spin currents, and spin waves, among others.

physics.optics↗

arXiv2019

Evolutionary optimization of all-dielectric magnetic nanoantennas

Magnetic light and matter interactions are generally too weak to be detected, studied and applied technologically. However, if one can increase the magnetic power density of light by several orders of magnitude, the coupling between magnetic light and matter could become of the same order of magnitude as the coupling with its electric counterpart. For that purpose, photonic nanoantennas have been proposed, and in particular dielectric nanostructures, to engineer strong local magnetic field and therefore increase the probability of magnetic interactions. Unfortunately, dielectric designs suffer from physical limitations that confine the magnetic hot spot in the core of the material itself, preventing experimental and technological implementations. Here, we demonstrate that evolutionary algorithms can overcome such limitations by designing new dielectric photonic nanoantennas, able to increase and extract the optical magnetic field from high refractive index materials. We also demonstrate that the magnetic power density in an evolutionary optimized dielectric nanostructure can be increased by a factor 5 compared to state of the art dielectric nanoantennas. In addition, we show that the fine details of the nanostructure are not critical in reaching these aforementioned features, as long as the general shape of the motif is maintained. This advocates for the feasibility of nanofabricating the optimized antennas experimentally and their subsequent application. By designing all dielectric magnetic antennas that feature local magnetic hot-spots outside of high refractive index materials, this work highlights the potential of evolutionary methods to fill the gap between electric and magnetic light-matter interactions, opening up new possibilities in many research fields.

cond-mat.mes-hall↗