Implementación de métodos numéricos para el análisis electromagnético de medios periódicos: aplicación en longitudes de onda ópticas y optimización computacional

This paper summarizes the contributions of a PhD focused on developing a set of numerical methods for the analysis of periodic diffractive optical devices such as holographic diffractive devices, thin film filters or diffraction gratings. For the rigorous and comprehensive analysis of these devices in optical wavelengths the finite difference time domain (DFDT) method was considered being compared to classical theories. Application of DFDT in optical wavelengths implies a considerable computational cost. Therefore, this method was accelerated for the most common computing platforms: CPU (Central Processing Unit) and GPU (Graphic Processing Unit).En este artículo se hace una revisión de las aportaciones de la Tesis Doctoral en la que se ha desarrollado una serie de métodos numéricos para el análisis de dispositivos ópticos difractivos periódicos como pueden ser Redes de Difracción Holográficas (RDH), filtros de capa delgada o redes de apertura. Para el análisis riguroso y completo de estos medios en longitudes de onda ópticas se ha recurrido al método de las diferencias finitas en el dominio del tiempo (DFDT), siendo contrastado mediante teorías clásicas. La aplicación del método de las DFDT en longitudes de onda ópticas implica un coste computacional considerable. Por ello, este método se ha acelerado en las plataformas de cálculo más comunes en la actualidad: CPU (Central Processing Unit) y GPU (Graphic Processing Unit).Este trabajo ha sido parcialmente financiado por el Ministerio de Economía y Competitividad de España a través del proyectos FIS2011-29803-C02-01, por la Universidad de Alicante a través del proyecto GRE12-14 y por la Generalitat Valenciana a través del proyecto GV/2014/076

Comment on “Application of Fresnel diffraction to nondestructive measurement of the refractive index of optical fibers”

We examine the validity of Eq. (5) in [A. Sabatyan and M. T. Tavassoly, “Application of Fresnel diffraction to nondestructive measurement of the refractive index of optical fibers,” Opt. Eng., 2007, Vol. 46(12), pp. 128001-1–128001-7] to describe the diffraction pattern of an optical fiber. We show that Eq. (5) must be changed to account for the phase introduced by the fiber correctly. In particular, we show that, to agree with the implicit criterion for representing traveling waves, given when using the Fresnel–Kirchoff integral [Eq. (4)], the phase introduced by the object must be carried by positive exponentials. The results obtained correcting Eq. (5) are compared with those obtained by the rigorous solution of Maxwell equations in the optical fiber. We demonstrate the importance of adequately taking into account the criterion implicitly assumed in the Fresnel–Kirchoff integral to represent traveling waves.This work was supported by the “Ministerio de Economía Industria y Competitividad” (Spain) under Project No. FIS2017-82919-R (MINECO/AEI/FEDER, UE)

Evaluación de Programas de Hipertensión en la Farmacia Comunitaria: revisión sistemática

Objetivo: Evaluar la literatura científica sobre los programas de Hipertensión Arterial llevados a cabo desde la Farmacia Comunitaria. Método: Estudio descriptivo y análisis crítico de los artículos recuperados en la revisión bibliográfica mediante técnica sistemática. Los datos se obtuvieron de la consulta directa y acceso, vía Internet, a las siguientes bases de datos bibliográficas del ámbito de las ciencias de la salud: MEDLINE (vía PubMed), Scopus, The Cochrane Library, EMBASE, Web Of Science, Institute for Scientific Information (ISI)., y Literatura Latinoamericana y del Caribe en Ciencias de la Salud (Lilacs). Se consideró apropiado el uso de los descriptores Farmacia (“Pharmacies”), Desarrollo de programa (“Program development”) e Hipertensión(“Hypertension”). Filtro Humanos. Resultados: Al atribuir los criterios de inclusión y exclusión a la búsqueda se aceptaron 10 estudios para su revisión y análisis crítico. Se evaluó la calidad de los artículos seleccionados mediante la declaración STROBE, obteniendo puntuaciones que oscilaron entre 7.5 y 14 sobre una puntuación máxima de 22. Conclusiones: Se han evaluado mediante revisión sistemática los resultados de la incorporación de un Servicio profesional Farmacéutico orientado a mejorar el uso de la medicación y los resultados de la farmacoterapia en pacientes hipertensos. La obsolescencia de los trabajos denotó la necesidad de artículos más actualizados y la producción científica sobre la materia puede considerarse escasa. Ningún programa de los evaluados puede ser considerado un Servicio Profesional Farmacéutico, ya que no ha tenido en cuenta todas las variables de forma integral e integrada, como proponen las directrices de la mayoría de las Sociedades Científicas. Sin embargo, los resultados pueden orientar sobre cómo implantar un Servicio Profesional Farmacéutico en la Farmacia Comunitaria

Aplicación del método de las DFDT a la simulación de dispositivos ópticos

[ES] La aplicación de las diferencias finitas en el dominio del tiempo (DFDT) para la simulación de dispositivos ópticos. En el rango de las longitudes de onda ópticas, la aplicación del método de las DFDT ha exigido un elevado coste computacional. La incorporación de distintas formulaciónes ha permitido la aplicación del algoritmo a sistemas ópticos.[EN] The aim of this work is to apply the difference time domain method for simulating optical devices. The wavelength used in optics makes harder the use of this algorithm in terms of time of processing. In this work different formalisms has been added such as near field to far field transformation, which has permitted to apply this algorithm to simulate optical devices like thin film filters and diffraction gratings. Satisfactory results has been achieved.The irradiance pattern obtained by the FDTD in far field (Fraunhofer region) is compared with analytical curves. Both curves are fit enough, as a result the algorithm has been validated. Rest of applications show the accuracy and potential of this algorithm applied to analyzing optical devices.Francés Monllor, J. (2009). Aplicación del método de las DFDT a la simulación de dispositivos ópticos. http://hdl.handle.net/10251/13049Archivo delegad

Analysis of all-optically tunable functionalities in sub-wavelength periodic structures by the Fourier modal method

We propose the nonlinear Fourier Modal Method (FMM) [J. Opt. Soc. Am. B 31, 2371 (2014)] as a convenient and versatile numerical tool for the design and analysis of grating based next generation all-optical devices. Here, we include several numerical examples where the FMM is used to simulate all-optically tunable functionalities in sub-wavelength periodic structures. At first, we numerically investigate a 1-D periodic nonlinear binary grating with amorphous TiO2. We plot the diffraction efficiency in the transmitted orders against the structure depth for normally incident plane wave. Change in diffraction efficiencies for different incident field amplitudes are evident from the plots. We verify the accuracy of our implementation by comparing our results with the results obtained with the nonlinear Split Field-Finite Difference Time Domain (SF-FDTD) method. Next we repeat the same experiment with vertically standing amorphous Titanium dioxide (TiO2) nanowire arrays grown on top of quartz which are periodic in two mutually perpendicular directions and examine the efficiencies in the direct transmitted light for different incident field amplitudes. Our third example includes analysis of a form birefringent linear grating with Kerr medium. With FMM we demonstrate that the birefringence of such a structure can be tuned by all-optical means. As a final example, we design a narrow band Guided Mode Resonance Filter (GMRF). Numerical experiments based on the nonlinear FMM reveal that the spectral tunability of such a filter can be obtained by all-optical means.This work is partially supported by the Academy of Finland (contract 285880)

Split-field finite-difference time-domain method for second-harmonic generation in two-dimensionally periodic structures

The split-field finite-difference time-domain method is extended to second-harmonic generation in two-dimensionally periodic structures. Making use of the full coefficient-tensor formalism, a coupled nonlinear system of equations, which must be solved at each update of the electromagnetic field, is developed. The accuracy of the method is verified by comparing the results to well-known one-dimensional problems. The results for L-shaped arrays are compared with results obtained with the Fourier modal method.This work is partially supported by the “Ministerio de Economía y Competitividad” of Spain under project FIS2011-29803-C02-01; by the “Generalitat Valenciana” of Spain under projects PROMETEO/2011/021, ISIC/2012/013, and GV/2014/076; and by the “Universidad de Alicante” of Spain under project GRE12-14

Registro de redes diente de sierra en fotopolímeros: efecto del sellante

Los fotopolímeros son unos materiales fotosensibles interesantes para el registro de elementos ópticos difractivos. No obstante el registro de perfiles de fase abruptos, como las redes de diente de sierra, presenta problemas por los rápidos cambios que tienen lugar en la superficie de estos materiales. En este trabajo se propone la utilización de sellantes con un índice de refracción promedio del fotopolímero para mejorar el registro de elementos difractivos abruptos.Financiado por Ministerio de Economía y Competitividad (FIS2011-29803-C02-01 y FIS2011-29803-C02-02), Generalitat Valenciana (PROMETEO/2011/021, ISIC/2012/013 y GV/2014/076), y Universidad de Alicante (GRE12-14)

Novel characterization methods and applications for photopolymers

Este trabajo ha sido financiado por el Ministerio de Economía y Competitividad (FIS2011-29803-C02-01 y FIS2011-29803-C02-02), por la Generalitat Valenciana (PROMETEO/2011/021, ISIC/2012/013) y por la Universidad de Alicante (GRE12-14)

Phase-Shift Optimization in AA/PVA Photopolymers by High-Frequency Pulsed Laser

Photopolymers can be used to fabricate different holographic optical elements, although maximization of the phase-shift in photopolymers has been a challenge for the last few decades. Different material compositions and irradiation conditions have been studied in order to achieve it. One of the main conclusions has been that with continuous laser exposure better results are achieved. However, our results show for the first time that higher phase-shift can be achieved using a pulsed laser. The study has been conducted with crosslinked acrylamide-based photopolymers exposed with a pulsed laser (532 nm). The increment of the phase-shift between the pulsed laser and continuous laser exposure is 17%, achieving a maximum phase-shift of 3π radians and a refractive index shift of 0.0084 at the zero spatial frequency limit, where monomer diffusion does not take place. This allows this photopolymer to be used in large-scale manufacturing.The work was supported by the “Ministerio de Ciencia e Innovación” of Spain under projects FIS2017-82919-R and PID2019-106601RB-I00 and by the “Universidad de Alicante” under project UATALENTO18-10

Manufacturing reflection holographic couplers for see-through applications recorded in photopolymers without prisms: an experimental validation

In the present work, the viability of a novel recording geometry to produce reflection holographic couplers is analyzed. Recalling the idea of previous works, photopolymers are used as the recording material, as they are well-suited for the intended see-through application. Moreover, Kogelnik’s theory fundamentals give us the proper background to examine the proposed design, where no prisms or microlenses arrays are used. Aiming to support the analysis, we provide experimental evidence that the produced gratings exhibit the correct properties to work as a coupler.Work supported by the “Generalitat Valenciana” (Spain) project PROMETEO/2021/006 and “Ministerio de Ciencia e Innovación” of Spain (project PID2021-123124OB-I00