Dye-Based Photonic Sensing Systems

[EN] We report on dye-based photonic sensing systems which are fabricated and packaged at wafer scale. For the first time luminescent organic nanocomposite thin-films deposited by plasma technology are integrated in photonic sensing systems as active sensing elements. The realized dye-based photonic sensors include an environmental NO2 sensor and a sunlight ultraviolet light (UV) A + B sensor. The luminescent signal from the nanocomposite thin-films responds to changes in the environment and is selectively filtered by a photonic structure consisting of a Fabry Perot cavity. The sensors are fabricated and packaged at wafer-scale, which makes the technology viable for volume manufacturing. Prototype photonic sensor systems have been tested in real-world scenarios.The authors thank the EU (Phodye Strep Project 033793 and ERC Starting Grant M&M's 277879), and the Spanish Ministry of Economy and Competitiveness (MAT-2010-21228) and Junta de Andalucia (P09-TEP-5283) for financial support.Aparicio, F.; Alcaire, M.; González-Elipe, A.; Barranco, A.; Holgado, M.; Casquel, R.; Sanza, F.... (2016). Dye-Based Photonic Sensing Systems. Sensors and Actuators B Chemical. 228:649-657. https://doi.org/10.1016/j.snb.2016.01.092S64965722

Quantitative Scanning Transmission Electron Microscopy–High-Angle-Annular Dark-Field Study of the Structure of Pseudo-2D Sb2Te3 Films Grown by (Quasi) Van der Waals Epitaxy

peer reviewedScanning transmission electron microscopy (STEM) techniques are used to improve the understanding of out-of-plane oriented Sb2Te3 thin films deposited by sputtering on SiO2 and Si substrates. Nanobeam precession electron diffraction, energy-dispersive X-ray spectroscopy, and high-angle-annular dark-field imaging show that the presence of 1–2 atomic planes of Te on top of the substrate is a crucial factor for successful growth of such films, which can be achieved by optimizing cosputtering of Te and Sb2Te3 targets. The formation of an actual van der Waals (vdW) gap between the substrate and the first Sb2Te3 quintuple layer allows for vdW epitaxy. This gap is larger than those separating Te planes in the pseudo-2D Sb2Te3 structure. HAADF image analysis provides detailed information on the atomic arrangement such as interplanar distances, vdW gaps, and Debye–Waller coefficients, all these with a few pm precision. For the anisotropic atomic displacements, a new methodology is introduced based on the statistical analysis of atomic column positions that provides information on the low-frequency phonon modes. Ab initio calculations are used to support our results. Overall, this study provides quantitative STEM tools particularly well suited for nonperiodic pseudo-2D materials, such as Sb2Te3/GeTe superlattices

Development of Photonic Multi-Sensing Systems Based on Molecular Gates Biorecognition and Plasmonic Sensors: The PHOTONGATE Project

[EN] This paper presents the concept of a novel adaptable sensing solution currently being developed under the EU Commission-founded PHOTONGATE project. This concept will allow for the quantification of multiple analytes of the same or different nature (chemicals, metals, bacteria, etc.) in a single test with levels of sensitivity and selectivity at/or over those offered by current solutions. PHOTONGATE relies on two core technologies: a biochemical technology (molecular gates), which will confer the specificity and, therefore, the capability to be adaptable to the analyte of interest, and which, combined with porous substrates, will increase the sensitivity, and a photonic technology based on localized surface plasmonic resonance (LSPR) structures that serve as transducers for light interaction. Both technologies are in the micron range, facilitating the integration of multiple sensors within a small area (mm2). The concept will be developed for its application in health diagnosis and food safety sectors. It is thought of as an easy-to-use modular concept, which will consist of the sensing module, mainly of a microfluidics cartridge that will house the photonic sensor, and a platform for fluidic handling, optical interrogation, and signal processing. The platform will include a new optical concept, which is fully European Union Made, avoiding optical fibers and expensive optical components.The micro-nanofabrication capabilities required in the PHOTONGATE project- 101093042 are funded by the Pluri-Regional FEDER funding Plan 2014-2020 European Commission. This research project has received funding from the European Union¿s HORIZON-CL4-2022 research and innovation programme under grant agreement ID 101093042, PHOTONGATE projectNieves-Paniagua, Ó.; Ortiz De Zárate-Díaz, D.; Aznar, E.; Caballos-Gómez, MI.; Garrido-García, EM.; Martínez-Máñez, R.; Dortu, F.... (2023). Development of Photonic Multi-Sensing Systems Based on Molecular Gates Biorecognition and Plasmonic Sensors: The PHOTONGATE Project. Sensors. 23(20):1-13. https://doi.org/10.3390/s23208548113232

Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

Transparent BaTiO3:Eu3+ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO3:Eu3+ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu3+ doped BaTiO3

Design status of ASPIICS, an externally occulted coronagraph for PROBA-3

The "sonic region" of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like conditions over long observation times. The space-borne coronagraphs flown so far provided a continuous coverage of the external parts of the corona but their over-occulting system did not permit to analyse the part of the white-light corona where the main coronal mass is concentrated. The proposed PROBA-3 Coronagraph System, also known as ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), with its novel design, will be the first space coronagraph to cover the range of radial distances between ~1.08 and 3 solar radii where the magnetic field plays a crucial role in the coronal dynamics, thus providing continuous observational conditions very close to those during a total solar eclipse. PROBA-3 is first a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future European missions, which will fly ASPIICS as primary payload. The instrument is distributed over two satellites flying in formation (approx. 150m apart) to form a giant coronagraph capable of producing a nearly perfect eclipse allowing observing the sun corona closer to the rim than ever before. The coronagraph instrument is developed by a large European consortium including about 20 partners from 7 countries under the auspices of the European Space Agency. This paper is reviewing the recent improvements and design updates of the ASPIICS instrument as it is stepping into the detailed design phase

The GenTree Platform: growth traits and tree-level environmental data in 12 European forest tree species

Background: Progress in the field of evolutionary forest ecology has been hampered by the huge challenge of phenotyping trees across their ranges in their natural environments, and the limitation in high-resolution environmental information. Findings: The GenTree Platform contains phenotypic and environmental data from 4,959 trees from 12 ecologically and economically important European forest tree species: Abies alba Mill. (silver fir), Betula pendula Roth. (silver birch), Fagus sylvatica L. (European beech), Picea abies (L.) H. Karst (Norway spruce), Pinus cembra L. (Swiss stone pine), Pinus halepensis Mill. (Aleppo pine), Pinus nigra Arnold (European black pine), Pinus pinaster Aiton (maritime pine), Pinus sylvestris L. (Scots pine), Populus nigra L. (European black poplar), Taxus baccata L. (English yew), and Quercus petraea (Matt.) Liebl. (sessile oak). Phenotypic (height, diameter at breast height, crown size, bark thickness, biomass, straightness, forking, branch angle, fructification), regeneration, environmental in situ measurements (soil depth, vegetation cover, competition indices), and environmental modeling data extracted by using bilinear interpolation accounting for surrounding conditions of each tree (precipitation, temperature, insolation, drought indices) were obtained from trees in 194 sites covering the species’ geographic ranges and reflecting local environmental gradients. Conclusion: The GenTree Platform is a new resource for investigating ecological and evolutionary processes in forest trees. The coherent phenotyping and environmental characterization across 12 species in their European ranges allow for a wide range of analyses from forest ecologists, conservationists, and macro-ecologists. Also, the data here presented can be linked to the GenTree Dendroecological collection, the GenTree Leaf Trait collection, and the GenTree Genomic collection presented elsewhere, which together build the largest evolutionary forest ecology data collection available

Between but not within species variation in the distribution of fitness effects

New mutations provide the raw material for evolution and adaptation. The distribution of fitness effects (DFE) describes the spectrum of effects of new mutations that can occur along a genome, and is therefore of vital interest in evolutionary biology. Recent work has uncovered striking similarities in the DFE between closely related species, prompting us to ask whether there is variation in the DFE among populations of the same species, or among species with different degrees of divergence, i.e., whether there is variation in the DFE at different levels of evolution. Using exome capture data from six tree species sampled across Europe we characterised the DFE for multiple species, and for each species, multiple populations, and investigated the factors potentially influencing the DFE, such as demography, population divergence and genetic background. We find statistical support for there being variation in the DFE at the species level, even among relatively closely related species. However, we find very little difference at the population level, suggesting that differences in the DFE are primarily driven by deep features of species biology, and that evolutionarily recent events, such as demographic changes and local adaptation, have little impact

Propriétés de superprisme des cristaux photoniques sur substrats SOI pour le démultiplexage en longueur d'onde

Ce travail de thèse constitue une contribution théorique et expérimentale aux études portant sur les cristaux photoniques (CPs) et leur utilisation pour le démultiplexage en longueur d'onde. Nous avons étudié la propagation de la lumière dans des CP bidimensionnels planaires sans défauts fabriqués à partir de substrats de silicium sur isolant. Pour cela, nous avons résolu le problème de réfraction entre un guide plan et un CP en utilisant le calcul 3D de leurs surfaces de dispersion. Des opérations supplémentaires sur celles-ci nous ont permis de caractériser la propagation des faisceaux dans le cristal et ainsi rechercher des structures permettant la réalisation de démultiplexeurs. Nos avons développé un procédé de fabrication de dispositifs à CPs sur SOI qui utilise les techniques de lithographie électronique et de gravure par plasma réactif. Nous avons étudié expérimentalement les effets de superprisme dans les CPs pour une large gamme de périodes et de facteurs de remplissage. Les phénomènes de dispersion observés ont pu être interprétés grâce aux modélisations développées, ce qui nous a permis de valider la méthode de calcul choisie. La compréhension des mécanismes de dispersion et la mise au point des étapes technologiques nous ont finalement permis de concevoir, réaliser, et caractériser un démultiplexeur CWDM à quatre canaux utilisant l'effet superprisme dans un cristal photonique. La structure présente une diaphonie de -16 dB pour un espacement en longueur d'onde de 25 nm, avec des pertes de 2 dB et une surface de cristal photonique de 2800 m .This PhD thesis brings a theoretical and experimental contribution to studies on photonic crystals (PCs) for wavelength demultiplexing. We have investigated light propagation within two dimensional planar PCs without defects, based on silicon on insulator (SOI) substrates. The modeling of light refraction at the interface between a planar waveguide and a PC has been achieved using 3D computations of the dispersion surfaces. Further calculations on band diagrams allowed characterizing the beam propagation inside the PC. Thanks to those calculations, PC structures have been explored for the realization of demultiplexers. A fabrication process of PCs on SOI substrates has been developed, using electron beam lithography and reactive ion etching technology. The superprism phenomena in PCs for a large panel of lattice size and filling factors have been experimentally studied. The observed dispersive effects correspond with modeling results. This agreement validated the calculation approach chosen for the problem. The understanding of dispersion effects and the development of the fabrication process has allowed designing, fabricating and characterizing a CWDM optical demultiplexer with four channels based on the superprism phenomena in PCs. The device presents a spectral spacing of 25 nm and a cross-talk level better than -16 dB using a 2800 m PhC region, with insertion losses of 2 dB.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Computation of light refraction at the surface of a photonic crystal using DtN approach

International audienceWhat we believe to be a new rigorous theoretical approach to the refraction of light at the interface of twodimensional photonic crystals is developed. The proposed method is based on the Dirichlet-to-Neumann (DtN) approach which consists of computing exactly the DtN operators associated with each half-space on both sides of the interface. It fully uses the properties of periodic optical media and takes naturally into account both the evanescent and propagative Bloch modes. Contrary to other proposed approaches, the new method is not based on modal expansions and their complicated electromagnetic field matching at the interfaces, but uses an operator vision. Intrinsically, each operator represents the effect along the interface of a particular medium independently of any medium and/or material that is placed in the other half-space. At the end, the whole computational effort to estimate DtN operators is restricted to the computation of a finite element problem in the periodicity cell of the photonic crystal. Field computations in arbitrary large part of the optical media can be then performed with a negligible computational effort. The method has been applied to the case of incoming plane waves as well as Gaussian beam profiles. It has successfully been compared with the standard plane wave expansion method and finite difference time domain (FDTD) simulations in the case of negative refraction, strongly dispersive, and lensing configurations. The proposed approach is amenable to the generalized study of dispersive phenomena in planar photonic crystals by a rigorous modeling approach avoiding the main drawbacks of FDTD. It is amenable to the study of arbitrary cascaded periodic optical media and photonic crystal heterostructures. © 2010 Optical Society of America

Growth mechanism of highly oriented layered Sb 2 Te 3 thin films on various materials

International audienc