Interacció Paramètrica no Lineal en Materials amb Nano-Estructuració Ordenada

Les interaccions no lineals de segon ordre són, probablement, uns dels processos de l'òptica no lineal més utilitzats i rellevants en quant a les seves aplicacions. Aquestes interaccions només són eficients en materials que presenten una simetria d'inversió i que permeten aconseguir-hi un mecanisme de phase matching. Això succeeix, en general, quan s'utilitzen materials amb un alt grau d'anisotropia, fet que imposa limitacions importants en les seves aplicacions. Des de fa temps s'utilitzen una gran varietat de cristalls inorgànics, com el LN o el KTP, en dispositius òptics comercials. Tanmateix aquests materials inorgànics tenen alguns inconvenients o limitacions com ara el cost, dificultats en el processat i poca flexibilitat per modificar-los i incorpora'ls-hi d'altres propietats. En aquest sentit les molècules orgàniques poden aportar solucions, però la dificultat d'assolir cristalls orgànics no centrosimètrics prou grans com per assolir eficiències semblants pel que fa als processos no lineals, n'ha limitat la seva aplicabilitat. Donada l'elevada no linealitat que s'obté amb algunes molècules orgàniques, les interaccions no lineals de superfície, són una de les possibilitats per aquest tipus de materials. Si bé l'eficiència d'un procés de superfície no és elevada, quan un és capaç de sumar coherentment els efectes d'un gran nombre de processos superficials, la interacció resultant pot ser eficient.Els cristalls fotònics són materials nanoestructurats amb la capacitat d'exercir un control ampli sobre la generació i propagació de la llum. Aprofitant els efectes en la propagació de la llum que es donen al llindar de les bandes prohibides, és possible exercir aquest control sobre les interaccions no lineals.Això, juntament amb el fet de que en un cristall fotònic hi ha un gran nombre de interfícies on dur a terme les interaccions no lineals, fa que sigui de gran interès realitzar un estudi exhaustiu de diferents interaccions paramètriques no lineals que s'hi poden considerar.En aquesta tesi es presenten estudis experimentals i teòrics sobre diferents interaccions no lineals considerades en el si de cristalls fotònics col·loïdals i d'òpals. En el cas dels cristalls col·loïdals, el treball es centra, majoritàriament, en l'estudi de les interaccions no lineals de segon ordre. Es demostra, que aquests processos que es poden aconseguir en el si d'una estructura centrosimètrica, són de superfície. Pel que fa als òpals, l'interès està centrat en conèixer com els efectes que aquests materials tenen sobre la velocitat de grup, poden aprofitar-se per incrementar l'eficiència de les interaccions no lineals.Fent ús de tècniques de síntesi en fase sòlida, s'ha pogut enllaçar un gran nombre de molècules no lineals a la superfície de nanoesferes de poliestirè. Aquestes esferes de làtex tenen la capacitat d'autoordenar-se en una xarxa cristal·lina centrosimètrica. Es demostra experimentalment que, gràcies a poder dur a terme una interacció no lineal de superfície en un material amb propietats de cristall fotònic, es poden assolir unes eficiències, 6 ordres de magnitud superiors a les assolides fins ara.Aquest treball comença amb una introducció, dels aspectes més rellevants dels cristalls fotònics i de l'òptica no lineal de segon ordre. Al capítol II es presenten les interaccions no lineals de segon ordre en cristalls col·loïdals. S'explica com es fabriquen aquestes estructures no lineals i es demostra experimentalment que la generació de segon harmònic en un cristall col·loïdal és un procés de superfície.Al capítol III de la tesi s'estudien la suma de freqüències contrapropagants i la generació de tercer harmònic en cristalls col·loïdals. Al capítol IV s'estudia, experimentalment, com es poden aprofitar les anomalies que apareixen en la velocitat de grup, quan la llum s'acobla a les bandes altes d'un òpal, per tal d'incrementar la generació de segon harmònic en aquestes estructures. Finalment, es presenten les conclusions del treball.Second order nonlinear interactions are, among, the most relevant nonlinear interactions between light and matter when one considers their applications. Such interactions are only efficient in noncentrosymmetric materials and materials or material structures that provide a phase matching mechanism. This is the case, for instance, in highly anisotropic crystals. However such anisotropy sets important limitations to the application scope of these materials.In the last decades, a large variety of inorganic crystals, such as, for instance, LN or KTP, have been used in optics devices. However, these inorganic materials have several drawbacks like their cost, processing difficulties and limitations to their flexibility and capability to hold new properties. Organic molecules may provide some alternatives, but the difficulties in getting a noncentrosymmetric organic crystal, large enough to hold an efficient nonlinear interaction, has restricted their applicability. Because the high nonlinearity of some organic molecules, one may consider surface nonlinear interaction as a good nonlinear mechanism for these molecules.Although the efficiency of surface interaction is low, when many of this surfaces interactions are coherently added, the whole process can be efficient. Photonic crystals have the capability of controlling the propagation and generation of light. Such control is larger in the neighbourhood of a forbidden band. In fact, at the edge of the band it is possible to control the nonlinear interactions. The high number of interfaces present in the photonic crystal structure, where a quadratic nonlinear interaction may occur, and the band edge effects, make it interesting to focus our study into some of such second order nonlinear interaction.In this thesis, we present experimental and theoretical results related to different second order nonlinear interactions in the framework of nonlinear colloidal photonic crystals, and nonlinear opals. For the colloidal crystals we mostly consider second order nonlinear processes, and the surface origin of these interactions is demonstrated. In the case of opals we focus our work on the effects that the group velocity anomalies present in the high bands of the photonic crystals, and show how we can take advantage of them for a nonlinear interaction enhancement.Using solid face methods, we have been able to covalently link a large amount of nonlinear organic molecules to the surfaces of polystyrene nanospheres. These latex spheres have the capability to self organise in a centrosymmetric lattice. We experimentally demonstrate that, given the photonic crystal properties of this material and the possibility of holding surface nonlinear interactions in the interfaces of the nanospheres, efficiencies up to 6 orders of magnitude larger than the ones obtained in the past, can be achieved.An introduction to relevant aspects of photonic crystals and nonlinear optics can be found in chapter I. In chapter II second order nonlinear interactions in photonic crystals are described.We explain how to fabricate these colloidal nonlinear crystals, and then experimentally demonstrate that second harmonic generation in the framework of colloidal photonic crystals is a surface phenomenon. In chapter III, counter-propagating sum frequency generation and third harmonic generation are discussed. In chapter IV, we experimentally demonstrate that, using an opal made of nonlinear polystyrene spheres, the enhancement of second harmonic generation is possible if one takes advantage of the group velocity anomalies presents on the edges of flat bands that are opened at higher frequencies. The main conclusions of the work are summarized in the last chapter

Crohn’s Disease Increases the Mesothelial Properties of Adipocyte Progenitors in the Creeping Fat

Malaltia de Crohn; Teixit adipós; MesoteliEnfermedad de Crohn; Tejido adiposo; MesotelioCrohn’s disease; Adipose tissue; MesotheliumOur understanding of the interplay between human adipose tissue and the immune system is limited. The mesothelium, an immunologically active structure, emerged as a source of visceral adipose tissue. After investigating the mesothelial properties of human visceral and subcutaneous adipose tissue and their progenitors, we explored whether the dysfunctional obese and Crohn’s disease environments influence the mesothelial/mesenchymal properties of their adipocyte precursors, as well as their ability to mount an immune response. Using a tandem transcriptomic/proteomic approach, we evaluated the mesothelial and mesenchymal expression profiles in adipose tissue, both in subjects covering a wide range of body-mass indexes and in Crohn’s disease patients. We also isolated adipose tissue precursors (adipose-derived stem cells, ASCs) to assess their mesothelial/mesenchymal properties, as well as their antigen-presenting features. Human visceral tissue presented a mesothelial phenotype not detected in the subcutaneous fat. Only ASCs from mesenteric adipose tissue, named creeping fat, had a significantly higher expression of the hallmark mesothelial genes mesothelin (MSLN) and Wilms’ tumor suppressor gene 1 (WT1), supporting a mesothelial nature of these cells. Both lean and Crohn’s disease visceral ASCs expressed equivalent surface percentages of the antigen-presenting molecules human leucocyte antigen—DR isotype (HLA-DR) and CD86. However, lean-derived ASCs were predominantly HLA-DR dim, whereas in Crohn’s disease, the HLA-DR bright subpopulation was increased 3.2-fold. Importantly, the mesothelial-enriched Crohn’s disease precursors activated CD4+ T-lymphocytes. Our study evidences a mesothelial signature in the creeping fat of Crohn’s disease patients and its progenitor cells, the latter being able to present antigens and orchestrate an immune response.This work was supported by grants from the Spanish Ministry of Science, Innovation and Universities (PI14/00228 and PI17/01503 to JV, SAF2015-65019-R to SF-V, BFU2015-70454-REDT and BFU2017-90578-REDT to SF-V and MMM, BFU2016-76711-R to MMM and PI15/00143 and PI18/00037 to CS) co-financed by the European Regional Development Fund (ERDF) and by Fundació La Marató de TV3 (PV170125) to SF-V and the European Crohn’s and Colitis Organization (ECCO) grant to CS. The Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM) (CB07708/0012) is an initiative of the Instituto de Salud Carlos III. AM is a recipient of a postdoctoral fellowship from FJCI-2014-23060 and IJCI-2016-30572. SF-V acknowledges support from the Miguel Servet tenure-track program (CP10/00438 and CPII16/00008) of the Fondo de Investigación Sanitaria, co-financed by the ERDF. C.S. acknowledges support from the ‘Ramón y Cajal’ program from MINECO (RYC2013-13186), co-financed by the ERDF

Sample holder for film or powder samples

[EN] Sample holder for performing measurements in a fluorimeter or UV-Vis-NIR spectrophotometer, the holder having a stage (1a) and a support (1b), the stage comprising two temperature adjustable metallic plates (7) opposed to each other, each provided with an optical window (12) in the center for holding a sample therebetween, a thermocouple (16) inserted in a hole (15) bored in one of the metallic plates (7), and electric heaters (9) embedded in each plate, wherein the support (1b) is capable of rotating for tuning the light incidence and/or light detection angle and the plates (7) are provided with magnets (13)Peer reviewedFundació institut Catala de Nanociéncia i Nanotecnologia, Consejo Superior de Investigaciones Científicas (España)A1 Solicitud de patente con informe sobre el estado de la técnic

Portamuestras para muestras de película o polvo

Portamuestras para realizar mediciones en un fluorímetro o un espectrofotómetro UV-Vis-NIR, la muestra tiene un soporte (1b) y una platina (1a) fijada a dicho soporte (1b), la platina comprende dos placas metálicas de temperatura ajustable (7) opuestas entre sí, cada una provista de una ventana óptica (12) en el centro para sostener una muestra entre ellas, un termopar (16) insertado en un orificio (15) taladrado en una de las placas metálicas (7), y calefactores eléctricos (9) integrados en cada placa, caracterizado por que el soporte (1b)es capaz de girar para ajustar el ángulo de incidencia de la luz y/o de detección de la luz con respecto a la platina (1a), y las placas (7) están provistas de imanes (13)Peer reviewedFundació institut Catala de Nanociéncia i Nanotecnologia, Consejo Superior de Investigaciones Científicas (España)U Solicitud de modelo de utilida

Specifications in stochastic process algebra for robot control problem

SIGLEGBUnited Kingdo

Light generation at the anomalous dispersion high energy range of a nonlinear opal film

We study experimentally and theoretically light propagation and generation at the high energy range of a close-packed fcc photonic crystal of polystyrene spheres coated with a nonlinear material. We observe an enhancement of the second harmonic generation of light that may be explained on the basis of amplification effects arising from propagation at anomalous group velocities. Theoretical calculations are performed to support this assumption. The vector KKR method we use allows us to determine, from the linear response of the crystal, the behavior of the group velocity in our finite photonic structures when losses introduced by absorption or scattering by defects are taken into account assuming a nonzero imaginary part for the dielectric constant. In such structures, we predict large variations of the group velocity for wavelengths on the order or smaller than the lattice constant of the structure, where an anomalous group velocity behavior is associated with the flat bands of the photonic band structure. We find that a direct relation may be established between the group velocity reduction and the enhancement of a light generation processes such as the second harmonic generation we consider. However, frequencies for which the enhancement is found, in the finite photonic crystals we use, do not necessarily coincide with the frequencies of flat high energy bands.Peer reviewe

Tautomeric enhancement of the hyperpolarizability in new acridine-benzothiazolylamine based NLO chromophores

The second order NLO response of a new family of acridine-based chromophores is greatly enhanced due to the presence of a tautomeric minor form with high charge-transfer capabilities.7 page(s

Low-Cost, User-Friendly, All-Integrated Smartphone-Based Microplate Reader for Optical-Based Biological and Chemical Analyses

The quantitative detection of different molecular targets is of utmost importance for a variety of human activities, ranging from healthcare to environmental studies. Bioanalytical methods have been developed to solve this and to achieve the quantification of multiple targets from small volume samples. Generally, they can be divided into two different classes: point of care (PoC) and laboratory-based approaches. The former is rapid, low-cost, and user-friendly; however, the majority of the tests are semiquantitative, lacking in specificity and sensitivity. On the contrary, laboratory-based approaches provide high sensitivity and specificity, but the bulkiness of experimental instruments and complicated protocols hamper their use in resource-limited settings. In response, here we propose a smartphone-based device able to support laboratory-based optical techniques directly at the point of care. Specifically, we designed and fabricated a portable microplate reader that supports colorimetric, fluorescence, luminescence, and turbidity analyses. To demonstrate the potential of the device, we characterized its analytical performance by detecting a variety of relevant molecular targets (ranging from antibodies, toxins, drugs, and classic fluorophore dyes) and we showed how the estimated results are comparable to those obtained from a commercial microplate reader. Thanks to its low cost (<$300), portability (27 cm [length] × 18 cm [width] × 7 cm [height]), commercially available components, and open-source-based system, we believe it represents a valid approach to bring high-precision laboratory-based analysis at the point of care.ICN2 is funded by CERCA programme, Generalitat de Catalunya. Grant SEV-2017-0706 funded by MCIN/AEI/10.13039/501100011033. The authors acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacer frente al impacto económico y social del COVID-19 (Ayudas CSIC-COVID-19)” and the research project INTCATCH 2020, Development and application of novel, integrated tools for monitoring and managing catchments supported by the European Union’s Horizon 2020 research and innovation program (Grant 689341). The authors also acknowledge the project MAT2017-87202-P funded by MCIN/AEI/10.13039/501100011033/and FEDER Una manera de hacer Europa. R.A.-D. acknowledges funding from the European Union Horizon2020 Programme under Grant No. 881603 (Graphene Flagship Core 3). A.I. was supported by PROBIST postdoctoral fellowship funded by the European Research Council (Marie Skłodowska-Curie grant agreement no. 754510)

Nonlinear generation of light in random structures

It is widely accepted that quadratic nonlinear processes, such as parametric generation or amplification, require the use of materials with a high degree of ordering. In some occasions, such ordering is found at a nanoscale, and in other cases, the order is at a micron scale. When such ordering is not intrinsic to the material, one may introduce a periodical distribution within the nonlinear material to, for instance, compensate the phase mismatch. In that event, the final material would be, in general, composed of two types of domains, distributed periodically across the entire material, one with a given nonlinear coefficient, and the other with the same coefficient with opposite sign. In principle, one would expect that small deviations from the adequate period, or some dispersion in the size of the domains, would lead to a cancellation of the coherent nonlinear process of three wave mixing. However, very recently, it was observed that with polycrystalline samples fabricated with a random orientation of zinc selenide (ZnSe) crystalline domains, when the average size of the domains was close to one coherence length (lcc), difference frequency generation grew linearly with the total length of the sample. Similar observations were reported some years ago from SBN needlelike crystalline domains and with the use of rotationally twinned crystals of ZnSe. In all these observations, the efficiency of the process seemed to be strongly linked to an average size of the domain close to the optimal value for quasi-phase matching with periodical inverted domains. In the present work, we study the process of phase matching to compensate the material dispersion in refractive index in materials where there is no structural ordering. We consider, here, one-dimensional (1-D) structures composed of planar layer domains with a well-defined orientation of the nonlinear susceptibility within the domain. Such domains, however, are randomly ordered and their thickness may vary - - with a Gaussian distribution around a given average size. In other words, the entire structure exhibits no ordering with respect to the orientation of the dipoles and the domains are allowed to have any possible thickness. Contrary to what one could expect, we observe that an increase in the amount of disorder is not necessarily detrimental with respect to the efficiency of a second harmonic generation (SHG) process. Moreover, the linear growth of the second harmonic (SH) intensity with respect to the number of domains is seen when the average size of the domains is close to one lc, but also, for any other average thickness of such domains. We are able to establish a clear link between the disorder inherent to the structure and the linear growth of the intensity with respect to the number of domains. It is also possible to obtain such type of nonlinear processes in random media where there is an index contrast between the several nonlinear domains. Recently significant progress has been made in the development in structured nonlinear materials. In the present paper we will review the performance of some of these nonlinear photonic materials that, eventually, could be implemented in a disordered configuration where the proposals of the present work could be experimentally tested.2 page(s

Nonlinear NanoOptics

This paper reviews the progress in implementing several new configurations to obtain a more flexible nonlinear optical interaction. In particular, this work reviews the experimental work on weak localization in nonlinear random media, second harmonic generation in the neighborhood of metallic nano particles, second harmonic from the high bands in opal structures, and second harmonic generation from the whispering gallery modes of microresonators.2 page(s