O espalhamento de ondas eletromagnéticas por partículas isoladas, com propriedades ópticas e formatos arbitrários, encontra aplicações nas mais diversas áreas do conhecimento. Usualmente, o espalhamento eletromagnético é investigado via grandezas auferidas na região de campo distante. Para partículas inomogêneas, no entanto, as ressonâncias nas seções de choque de espalhamento podem não corresponder a um aumento de intensidade do campo eletromagnético nas vizinhanças imediatas da partícula (região de campo próximo). Esse efeito pode ser induzido em nanopartículas dielétricas com revestimentos plasmônicos e foi recentemente explicado em termos da ressonância de Fano. Essa ressonância resulta da interferência entre um modo eletromagnético não ressonante (processo de fundo) e um modo discreto ressonante (ressonância de plásmon), produzindo um formato assimétrico de linha espectral. Para o entendimento de como os modos de superfície no campo próximo acoplam-se às ressonâncias nas seções de choque, é necessário o cálculo de funcionais dos campos eletromagnéticos internos às partículas ou em suas vizinhanças imediatas. Neste estudo, calculamos a energia eletromagnética no interior de centros espalhadores nas geometrias esférica e cilíndrica. Fazemos aqui o vínculo dos campos internos às grandezas de espalhamento no campo distante via seção de choque de absorção e conservação de energia. Aplicamos nossos resultados a metamateriais dispersivos, estudando as propriedades do espalhamento por esferas revestidas e por esferas quirais, no regime de refração negativa, e por cilindros revestidos sob incidência oblíqua de radiação. Mediante a energia interna às partículas, demonstramos novos efeitos de aumento de intensidade de campo interno fora da ressonância de espalhamento e fornecemos resultados analíticos para a análise dessas ressonâncias, tanto em espalhamento simples quanto múltiplo. / Electromagnetic wave scattering by single particles with both shapes and optical properties arbitrary finds applications in several areas of knowledge. Usually, the electromagnetic scattering is investigated via measured quantities in the far-field region. However, for inhomogeneous particles, resonances in scattering cross sections may not correspond to the electromagnetic field enhancement in the vicinity of a particle (near-field). This effect can be induced in dielectric nanoparticles with plasmonic coatings, and it has recently been explained in terms of the Fano resonance. The Fano resonance results from the interference between a non-resonant electromagnetic mode (background or continuous) and a resonant discrete mode (localized plasmon resonance), leading to an asymmetric lineshape. To understand how the surface modes in the near-field are connected to the cross section resonances, functionals of the electromagnetic fields within scatterers or in their vicinity are required. In this study, we calculate the electromagnetic energy inside scatterers in both cylindrical and spherical geometries. We obtain a connection between the internal energy and the scattering quantities in the far-field via absorption cross section and energy conservation. We apply our results to dispersive metamaterials, studying scattering properties of coated and chiral spheres in the negative refraction regime, and coated cylinders under oblique incidence of radiation. By the electromagnetic energy inside particles, we demonstrate new off-resonance field enhancement effects and provide analytical tools to analyze these resonances in both single and multiple scattering regimes.

Orientador: Carlos Lenz Cesar / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física "Gleb Wataghin" / Made available in DSpace on 2018-08-18T09:30:54Z (GMT). No. of bitstreams: 1 Moreira_WendelLopes_D.pdf: 1772489 bytes, checksum: 3d4e37a805f4c66c447aea58b93692b8 (MD5) Previous issue date: 2010 / Resumo: Desde 1908, quando Mie apresentou expressões analíticas para os campos espalhados por uma partícula esférica sob incidência de uma onda eletromagnética plana, generalizações para esta expansão têm se mostrado incompletas. Isto se deve à presença de certos termos com dependência radial nos coe cientes de forma do feixe quando expandido em termos de funções de onda esféricas vetoriais. Aqui mostramos pela primeira como cancelar estes termos, permitindo expressões analíticas para os coe cientes para um campo eletromagnético completamente arbitrário. Damos tambem vários exemplos deste novo método, que também é muito apropriado para cálculos numéricos. Obtemos deste modo, expressões analíticas para feixes de Bessel e para os modos de guias de onda metálicos retangulares e cilíndricos. Estes resultados são extremamente relevantes para o incremento na velocidade de cálculo das forças de radiação atuando sobre uma partícula esférica, colocada em um campo eletromagnético arbitrário, com por exemplo, em pinças ópticas / Abstract: Since 1908, when Mie reported analytical expressions for the elds scattered by a spherical particle upon incidence of an electromagnetic plane-wave, generalizing his analysis to the case of an arbitrary incident wave has proved elusive. This is due to the presence of certain radially-dependent terms in the equation for the beam-shape coecients of the expansion of the electromagnetic elds in terms of vector spherical wave functions. Here we show for the rst time how these terms can be canceled out, allowing analytical expressions for the beam shape coecients to be found for a completely arbitrary incident eld. We give several examples of how this new method, which is well suited to numerical calculation, can be used. Analytical expressions are found for Bessel beams and the modes of rectangular and cylindrical metallic waveguides. The results are highly relevant for speeding up calculation of the radiation forces acting on spherical particles placed in an arbitrary electromagnetic eld, such as in optical tweezers / Doutorado / Física / Doutor em Ciências

Dans ce mémoire, je propose une nouvelle technique optique de mesure de positions relatives 3D, tailles et indices de réfraction d’un ensemble de particules, éclairées par un faisceau laser plan pulsé : l’imagerie interférométrique de Fourier (FII). Dans le cadre de ce travail, les particules sont sphériques, homogènes transparentes et isotropes. Lorsque ces particules sont éclairées, elles se comportent comme des sources d’ondes lumineuses sphériques qui interférent entre elles. L’enregistrement des franges d’interférences et leur analyse par transformation de Fourier peut permettre d’accéder aux caractéristiques des particules. Dans ce mémoire, je décris l’influence des caractéristiques de particules sur les représentations spectrales des franges d’interférences crées par les couples de particules éclairées dans l’espace de Fourier 2D. Les franges d’interférences sont simulées numériquement en utilisant la théorie de Lorenz-Mie. Puis j’aborde le problème inverse en montrant comment il est possible de retrouver les caractéristiques des particules, en me servant de l’optique géométrique et du filtrage spatial par transformation de Fourier. / In this thesis, I propose a new optical technique for measuring 3D relative positions, sizes and refractive indices of a set of particles, which are illuminated by a plane and pulsed laser beam. In this work, the particles are spherical, transparent, homogeneous and isotropic. When these particles are illuminated, they have the behavior of sources of spherical light waves which interfere. The recording of interference fringes and analysisby Fourier transform can measure the characteristics of the particles. I describe the influence of particle characteristics on spectral representations of the interference fringes created by the pairs of particles illuminated in 2D Fourier space. The interference fringes are simulated numerically using the Lorenz-Mietheory. The inverse problem is approached by showing how it is possible to measure the characteristics of particles with geometrical optics and spatial filtering by Fourier transformation.

[pt] Neste trabalho foi feito o estudo do espalhamento da luz realizado por partículas esféricas dielétricas, pelo uso do método dos elementos finitos, através do software COMSOL Multiphysics 5.6, sendo considerado o comportamento da luz tanto como onda quanto como partícula. Este estudo visa, no futuro, a compreensão do laser aleatório em sistemas com centros espalhadores de diferentes geometrias. Considerando o comportamento ondulatório da luz, foi estudada a teoria sobre as séries de Mie. Esta, por sua vez, é uma solução que, dado o campo de incidência, pode-se calcular os campos espalhados e absorvidos por partículas esféricas. Foram calculados os valores da seção de choque de espalhamento e a média do cosseno do ângulo de espalhamento para uma partícula de raio (r) maior que um décimo do comprimento de onda (Comprimento de onda) da luz (raio maior que um décimo do comprimento de onda) e uma com (raio menor que um décimo do comprimento de onda). Neste último caso, também foi estudada a variação da intensidade da luz espalhada em função do ângulo de espalhamento. Os resultados das partículas pequenas corresponderam ao regime de Rayleigh. As partículas esféricas consideradas foram a rutila, TiO2, e a alumina, Al2O3. Foi estudado também o espalhamento de luz realizado por duas partículas idênticas. Para esse caso, obteve-se uma luz espalhada mais intensa na região entre as partículas em comparação a outras regiões. Ademais, ao comparar com o espalhamento feito por uma única partícula, foi notado que a luz espalhada por duas partículas, na região entre as duas, também era mais intenso. Além disso, ao estudar o confinamento de luz entre duas e três partículas de r = 230 nm, viu-se que o espectro do campo espalhado apresentava mais de um pico, como há em lasers aleatórios coerentes. No que concerne ao comportamento corpuscular da luz, foi considerada a equação de difusão de fótons, onde o espectro de emissão da fluorescência de R6G incidindo em uma concentração da ordem de 1010 cm−3 partículas foi simulado e, posteriormente, comparou-se o resultado obtido com o comportamento de um sistema de laser aleatório incoerente. / [en] In this work, the study of light scattering performed by dielectric spherical particles was carried out, using the finite element method, through the COMSOL Multiphysics 5.6 software, considering the behavior of light both as a wave and as a particle. This study aims, in the future, to understand the random laser in systems with scatter centers with different geometries. Considering the wave behavior of light, the theory of the Mie series was studied. This is a solution that, given the incidence field, makes it possible to calculate the fields scattered and absorbed by the spherical particles. The values of the scattering cross section and the mean of the cosine of the scattering angle were calculated for a particle with radius (r) bigger than one tenth of the light wavelength (wave length) (radius greater than one tenth of the wave length) and one with (radius less than one tenth of the wave length). In the latter case, the variation of the scattered light intensity as a function of the scattering angle was also studied. The small particle results corresponded to the Rayleigh regime. The spherical particles considered were rutile, TiO2, and aluminium oxide, Al2O3. The scattering of light performed by two identical particles was also studied. For this case, a more intense scattered light was obtained in the region between the particles compared to other regions. Furthermore, when comparing with the scattering done by a single particle, it was noticed that the light scattered by two particles, in the region between the two, was also more intense. Furthermore, when studying the confinement of light between two and three particles with r = 230 nm, it was seen that the spectrum of the scattered field showed more than one peak, as one has in coherent random lasers. Concerning the corpuscular behavior of light, the photon diffusion equation was considered, where the emission spectrum of the fluorescence of R6G incident on a concentration of the order of 1010 cm−3 particles was simulated and, later, the result obtained was compared with the behavior of an incoherent random laser system.

Diese Arbeit beschäftigt sich mit der Simulation von Streuung und Absorption von elektromagnetischen Wellen in Gewebephantomen im Kontext optischer Cochlea-Implantate. Dabei werden wellen- und strahlenoptische Ansätze diskutiert und auf ihre Eignung für die Modellierung des Streuverhaltens in gewebeähnlichen Schichten untersucht. Im Einzelnen werden FDTD-Simulationen mit einem Mie-Streuprogramm verglichen, sowie Monte-Carlo-Simulationen durchgeführt. Die gewonnenen Daten für Gewebephantome werden mit einem experimentellem Ansatz und Literaturwerten für echtes Gewebe verglichen. Es wird gezeigt unter welchen Parametern die Lichtstreuung optimal für die gewünschte Anwendung in optischen Cochlea-Implantaten ist. Weiterhin ergibt sich, im Rahmen dieser Arbeit, die Monte-Carlo-Simulation in Verbund mit einem Mie-Streuprogramm als die praktikabelste Lösung, um mit Experiment und Literatur vergleichbare Schichtdicken zu simulieren und entsprechende Ergebnisse zu gewinnen. Die Übereinstimmung zwischen Simulationen und experimentellen Daten lies sich für Gewebephantome nachweisen. Weiterhin konnten erste Schlüsse über die Übereinstimmung des Verhaltens dieser Phantome gegenüber echter menschlicher Dermis gezogen werden. / This work addresses the simulation of scattering and absorption of electromagnetic waves in tissue phantoms in the context of optical cochlear implants. Wave-optical and ray-optical approaches are discussed and investigated for their suitability for modeling the scattering behavior in tissue-like layers. Specifically, FDTD simulations are compared with a Mie-scattering program, and Monte Carlo simulations are performed. The obtained data for tissue phantoms will be compared with an experimental approach and literature values for real tissue. It is shown under which parameters the light scattering is optimal for the desired application in optical cochlear implants. Furthermore, in the context of this work, the Monte-Carlo simulation in combination with a Mie-scattering program is most practicable to simulate layer thicknesses comparable to experiment and literature and to obtain the corresponding results. The agreement between simulations and experimental data could be demonstrated for tissue phantoms. Furthermore, first conclusions could be drawn about the agreement of the behavior of these phantoms compared to real human dermis.

[ES] Las nanopartículas de alto índice admiten multipolos electromagnéticos que determinan su respuesta a una onda incidente. Cuando se excitan diferentes multipolos, estos pueden interferir, dando lugar a fenómenos sorprendentes. Por ejemplo, a partir de la oscilación en antifase del dipolo toroidal y eléctrico (o magnético) cartesiano o de los correspondientes multipolos de orden superior surgen los llamados estados anapolares, caracterizados por una reducción sustancial de la dispersión de campo lejano y una fuerte localización de la energía dentro del disco. Una de las estructuras de alto índice más sencillas que soportan la interferencia multipolar es el disco, que se puede construir fácilmente sobre un sustrato de sílice utilizando herramientas estándar de nanofabricación de silicio. La mayoría de los estudios de estados de anapolos en discos dieléctricos de alto índice han abordado anapolos que pueden excitarse bajo iluminación normal, pero la incidencia en el plano es necesaria para construir circuitos integrados fotónicos de silicio cuando la luz está completamente unida al plano del chip. En esta tesis investigamos mediante simulaciones numéricas anexas a medidas experimentales la aparición de interferencias multipolares en discos de silicio cuando excitamos en el plano a través de guías de ondas. Primero, investigamos los efectos en discos aislados del tamaño de una sublongitud de onda y luego ampliamos nuestra investigación a cadenas periódicas unidimensionales. Bajo la excitación en el plano de un disco de silicio del tamaño de una sublongitud de onda, observamos anapolos magnéticos y eléctricos de varios órdenes, cambiando la geometría del sistema. Curiosamente, observamos un desacoplamiento del mínimo en la dispersión de campo lejano y el máximo de localización de energía en el disco, que tienen lugar en longitudes de onda bien separadas para la excitación en el plano del anapolo en comparación con el caso de incidencia normal habitual. Por otro lado, a través de la excitación del dipolo toroidal, demostramos la transmisión eficiente por encima del cono de luz en una estructura periódica formada por discos de silicio del tamaño de una sublongitud de onda. Finalmente, predecimos el cierre de la banda prohibida de Bragg debido a la interacción entre dipolos eléctricos y magnéticos en una estructura periódica formada por nanobloques de silicio. Nuestros resultados resaltan diferencias significativas entre las interferencias multipolares cuando las partículas se iluminan desde diferentes direcciones y tienen implicaciones directas para el uso de discos del tamaño de la longitud de onda en circuitos integrados fotónicos de alto índice para aplicaciones que van desde la biodetección y la espectroscopia hasta el procesamiento de señales no lineales. / [CA] Les nanopartícules d'alt índex admeten multipols electromagnètics que determinen la seua resposta a una ona incident. Quan s'exciten diferents multipols, aquests poden interferir, donant lloc a fenòmens sorprenents. Per exemple, a partir de l'oscil·lació en antifase del dipol toroidal i elèctric (o magnètic) cartesià, o dels corresponents multipols d'ordre superior, sorgeixen els anomenats estats anapolars, caracteritzats per una reducció substancial de la dispersió de camp llunyà i una forta localització de l'energia dins del disc. Una de les estructures d'alt índex més senzilles que suporten la interferència multipolar és el disc, que es pot construir fàcilment sobre un substrat de sílice utilitzant eines estàndard de nano fabricació de silici. La majoria dels estudis d'estats d'anapols en discos dielèctrics d'alt índex han abordat anapols que poden excitar-se sota il·luminació normal, però la incidència en el pla és necessària per a construir circuits integrats fotònics de silici quan la llum està completament unida al pla del xip. En aquesta tesi investiguem mitjançant simulacions numèriques annexes a mesures experimentals l'aparició d'interferències multipolars en discos de silici quan excitem en el pla a través de guies d'ones. Primer, investiguem els efectes en discos aïllats de la grandària d'una sublongitud d'ona i després ampliem la nostra investigació a cadenes periòdiques unidimensionals. Sota l'excitació en el pla d'un disc de silici de la grandària d'una sublongitud d'ona, observem anapols magnètics i elèctrics de diversos ordres, canviant la geometria del sistema. Curiosament, observem un desacoblament del mínim en la dispersió de camp llunyà i el màxim de localització d'energia en el disc, que tenen lloc en longituds d'ona ben separades per a l'excitació en el pla del anapol en comparació amb el cas d'incidència normal habitual. D'altra banda, a través de l'excitació del dipol toroidal, vam demostrar la transmissió eficient per damunt del con de llum en una estructura periòdica formada per discos de silici de la grandària d'una sublongitud d'ona. Finalment, prediem el tancament de la banda prohibida de Bragg a causa de la interacció entre dipols elèctrics i magnètics en una estructura periòdica formada per nanobloques de silici. Els nostres resultats ressalten diferències significatives entre les interferències multipolars quan les partícules s'il·luminen des de diferents direccions i tenen implicacions directes per a l'ús de discos de la grandària de la longitud d'ona en circuits integrats fotònics d'alt índex per a aplicacions que van des de la biodetecció i l'espectroscòpia fins al processament de senyals no lineals. / [EN] High-index nanoparticles support electromagnetic multipoles that determine their response to an incident wave. When different multipoles are excited, they can interfere, giving rise to surprising phenomena. For example, from the antiphase oscillation of the Cartesian toroidal and electric (or magnetic) dipole or the corresponding higher-order multipoles arise the so-called anapole states, characterized by a substantial reduction in the far-field scattering and a strong localization of energy inside the disk. One of the simplest high-index structures supporting multipolar interference is the disk, which can be easily built on a silica substrate using standard silicon nanofabrication tools. Most studies of anapole states in high-index dielectric disks have addressed anapoles that can be excited under normal illumination, but the in-plane incidence is necessary for building silicon photonic integrated circuits (PICs) when light is completely bound to the chip plane. In this thesis, we investigate via numerical simulations annex experimental measurements the appearance of multipolar interferences in silicon disks when we excited in-plane through waveguides. First, we investigate the effects on isolated subwavelength-sized disks and then extend our investigation to one-dimensional (1D) periodic chains. Under the in-plane excitation of a silicon subwavelength-sized disk, we observe magnetic and electric anapoles of various orders, changing the geometry of the system. Interestingly, we observed a decoupling of the minimum in the far-field scattering and the maximum of energy localization in the disk, which takes place at well-separated wavelengths for in-plane excitation of the anapole as compared to the usual normal incidence case. On the other hand, through the excitation of the toroidal dipole, we demonstrate the efficient transmission above the light cone in a periodic structure formed by silicon subwavelength-sized disks. Finally, we predict the closure of the Bragg bandgap due to the interaction between electric and magnetic dipoles in a periodic structure formed by silicon nanobricks. Our results highlight significant differences between multipoles interferences when the particles are illuminated from different directions and have direct implications for the use of wavelength-size disks in high-index PICs for applications ranging from biosensing and spectroscopy to nonlinear signal processing. / Debo agradecer a la Generalitat Valenciana que con su programa de becas Santiago Grisolía GRISOLIAP/2018/164 me permitió comenzar este camino. Al Instituto de Tecnología Nanofotónica y a la Universidad Politécnica de Valencia por darme la oportu- nidad de labrar mi camino hacia el título de Doctor of Philosophy in Telecommunications Engineering en sus instalaciones. / Díaz Escobar, E. (2023). Investigation of Multipolar Interference in Silicon Disks for on-Chip Photonics [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/192830

Aerosols of nitrate solutions were irradiated in the presence of radical scavengers in an attempt to measure the yield of hydroxyl radical in both the aqueous phase and the gas phase. Carbon monoxide, benzoic acid, benzene and cyclohexane were used as scavengers to trap hydroxyl radical. The products from the reaction of these scavengers with hydroxyl radical were analysed with High Performance Liquid Chromatography and mass spectrometry. The radiant flux in the chamber was measured via ferrioxalate actinometry, both with bulk liquid and aerosol droplets. Many quantitative results were obtained but several anomalies were found. This suggests that Mie theory is not capable of predicting rates of photochemical reactions within droplets.

Mineral dust aerosol plays an important role in determining the physical and chemical equilibrium of the atmosphere. The radiative balance of the Earth's atmosphere can be affected by mineral dust through both direct and indirect means. Mineral dust can directly scatter or absorb incoming visible solar radiation and outgoing terrestrial IR radiation. Dust particles can also serve as cloud condensation nuclei, thereby increasing albedo, or provide sites for heterogeneous reactions with trace gas species, which are indirect effects. Unfortunately, many of these processes are poorly understood due to incomplete knowledge of the physical and chemical characteristics of the particles including dust concentration and global distribution, as well as aerosol composition, mixing state, and size and shape distributions. Much of the information about mineral dust aerosol loading and spatial distribution is obtained from remote sensing measurements which often rely on measuring the scattering or absorption of light from these particles and are thus subject to errors arising from an incomplete understanding of the scattering processes. The light scattering properties of several key mineral components of atmospheric dust have been measured at three different wavelengths in the visible. In addition, measurements of the scattering were performed for several authentic mineral dust aerosols, including Saharan sand, diatomaceous earth, Iowa loess soil, and palagonite. These samples include particles that are highly irregular in shape. Using known optical constants along with measured size distributions, simulations of the light scattering process were performed using both Mie and T-Matrix theories. Particle shapes were approximated as a distribution of spheroids for the T-Matrix calculations. It was found that the theoretical model simulations differed markedly from experimental measurements of the light scattering, particularly near the mid-range and near backscattering angles. In many cases, in the near backward direction, theoretical models predicted scattering intensities for near spherical particles that were up to 3 times higher than the experimentally measured values. It was found that better agreement between simulations and experiments could be obtained for the visible scattering by using a much wider range of more eccentric particle shapes.

Remote sensing is the collection of information about an object from a distance without physically being in contact with it. The type of remote sensing of interest here is in the form of digital images of water bodies acquired by satellite. The advantage over traditional sampling techniques is that data can be gathered quickly over large ranges, and be available for immediate analysis. Remote sensing is a powerful technique for the monitoring of water bodies. To interpret the remotely sensed data, however, knowledge of the optical properties of the water constituents is needed. One of the most important of these is the volume scattering function, which describes the angular distribution of light scattered by a sample. This thesis presents the first measurements of volume scattering functions for Australian waters. Measurements were made on around 40 different samples taken from several locations in the Gippsland lakes and the Great Barrier Reef. The measurements were made by modifying an existing static light scattering spectrometer in order to accurately measure the volume scattering functions. The development of the apparatus, its calibration and automation, and the application of a complex series of post-acquisition data corrections, are all discussed. In order to extrapolate the data over the full angular range, the data was analysed using theoretical curves calculated for multi-modal size distributions using Mie light scattering theory applied to each data set. From the Mie fits the scattering and backscattering coefficients were calculated. These were compared with scattering coefficients measured using in situ sensors ac-9 and Hydroscat-6, and with values from the literature. The effect of chlorophyll a concentrations on the scattering coefficients was examined, and a brief investigation of the polarisation properties of the samples was also undertaken. Finally the angular effects on the relationship between the backscattering coefficient and the volume scattering function were investigated. This is important as in situ backscattering sensors often assume that measuring at a single fixed-angle is a good approximation for calculating the backscattering coefficient. This assumption is tested, and the optimal measurement angle determined.

Ce travail présente d'une part la fabrication d'entités nanométriques (nanocouches, nanoparticules) photochromes et d'autre part les méthodes de détection ou d'amplification de leur commutation. Des nanoparticules de diaryléthène ont été obtenues par fragmentation laser. Leur caractère photochrome en solution colloïdale a été mis en évidence par des mesures d'ensemble en spectroscopie d'absorption, mais également au niveau de la particule unique par la spectroscopie de diffusion en champ sombre. Ces nanoparticules ont montré des propriétés différentes de celles en solution et de celles à l'état solide illustrées par des rendements quantiques différents. Pour comparer les rendements quantiques des différents états, une méthode numérique a été mise au point pour l'étude à l'état solide. L'obtention de systèmes hybrides par dépôt de couches minces de photochromes sur des substrats recouverts de nanoparticules d'or a permis de mettre en évidence une nouvelle approche pour détecter la photocommutation aux petites échelles. Cette commutation du photochrome provoque un déplacement intense et réversible en longueur d'onde de la bande des plasmons de surface localisée (PLS) des nanoparticules d'or. Cette observation est corrélée à des calculs basés sur le formalisme de Mie. De plus, l'exaltation du champ électromagnétique par excitation des PLS a permis d'accélérer la réaction photochrome dans le sens de la décoloration, renforçant l'intérêt de ces matériaux hybrides pour le stockage de données.