This work shows the redesign of an elemental experience based on the Helmholtz resonator using 3D printing. A Helmholtz resonator is based on a volume and at least one opening that can include a tube or not. The air column inside the tube can be considered the mass of the system, whereas the volume represents the system’s stiffness. Due to these analogies between acoustics and mechanics, the Helmholtz resonator is an interesting example of a harmonic oscillator. The relevance of harmonic motions is well known, and this topic is present in the syllabus of many technical and scientific education degrees. In this work, a bottle has been designed and fabricated using 3D printer technology. The design aimed to create a Helmholtz resonator with a variable frequency of resonance. Different mouthpieces have also been designed. The bottle is composed of a set of cylindrical sections that can be attached, enlarging the length of the container. For ensuring that the different parts set a tight enclosure, an O-ring seal has also been designed and fabricated. As more rings and O-seal junctions are attached, the volume of the resonator grows. By blowing the mouth of the Helmholtz resonator with different sections, different resonance frequencies can be measured. From these measurements, several parameters can be estimated indirectly, such as the speed of sound waves, the room temperature, and air density. 3D printing permits to analyse several scenarios without using uncomfortablestrategies to vary the bottle’s volume, such as water, reducing the hazard in a laboratory with electronic instrumentation.

This work presents recent results derived from the rigorous modelling of holographic polymer-dispersed liquid crystal (H-PDLC) gratings. More precisely, the diffractive properties of transmission gratings are the focus of this research. This work extends previous analysis performed by the authors but includes new features and approaches. More precisely, full 3D numerical modelling was carried out in all analyses. Each H-PDLC sample was generated randomly by a set of ellipsoid geometry-based LC droplets. The liquid crystal (LC) director inside each droplet was computed by the minimisation of the Frank elastic free energy as a function of the applied electric field. The analysis carried out considered the effects of Frank elastic constants K11, K22 and K33; the anchoring strength W0; and even the saddle-splay constant K24. The external electric field induced an orientation of the LC director, modifying the optical anisotropy of the optical media. This effect was analysed using the 3D split-field finite-difference time-domain (SF-FDTD) method. In order to reduce the computational costs due to a full 3D tensorial analysis, a highly optimised method for high-performance computing solutions (HPC) was developed. The influences of the anchoring and voltage on the diffraction efficiencies were investigated, showing the potential of this approach.

Uno de los factores de exito mas importantes en el ambito educativo corresponde a la motivacion del alumno. Por tanto, resulta de vital importancia conocer sus expectativas y tenerlas en cuenta a la hora de establecer una planificacion docente apropiada. El grado en Ingenieria en Sonido e Imagen en Telecomunicacion en la Universidad de Alicante, cuenta con un itinerario formativo en el area de Ingenieria Acustica. Esta investigacion surge como iniciativa para la mejora de la actividad docente en dicho itinerario y sus objetivos se centran en conocer las expectativas del alumnado en relacion a diferentes aspectos del mismo. El estudio, de tipo cuantitativo, se llevo a cabo por medio de encuestas en las que participaron un total de 69 alumnos. Los resultados ponen de manifiesto un gran desconocimiento de las materias impartidas en el itinerario, asi como de las salidas profesionales asociadas a la Ingenieria Acustica. De acuerdo con las preferencias del alumnado, resulta primordial orientar los programas docentes a las demandas del mercado laboral. Asimismo, los contenidos practicos y la incorporacion en el proceso formativo de charlas o debates realizados por expertos del sector pueden ayudar en gran medida a lo largo del proceso de aprendizaje.

In this work we study and characterize and holographic waveguide system composed of two volume diffraction gratings, which act as optical couplers and a glass substrate that acts as a waveguide. The features such us high diffraction efficiencies and Bragg angle selectivity exhibited by volume diffraction gratings allow the appropriated adjustment of the incident light to be diffracted in the direction of total reflection condition inside the glass substrate with high efficiency. In this work the holographic waveguide is recorded on different photopolymer materials, which optimization is controlled to obtain high spatial frequencies and stable fringes. The effect of the shrinkage of the holograms after recording in the quality of the image obtained from the optical waveguide is also studied. To perform the experiments two kind of photopolymers were studied: a nanoparticle-(thiol-ene) polymer composite, NPC, and a penta/hexa-acrylate based polymer with dispersed nematic liquid crystal molecules, PDLC. The holographic characteristics such as diffraction efficiency or wavelength selectivity obtained with the waveguides recorded on the different photopolymers were also studied and compared.

The possibilities that offer the holographic optical elements for photovoltaic and "see through display" applications open new windows for holographic recording materials. In this sense, some specific characteristics are required for each particular application. Waveguides are one of the key elements for these applications. Photopolymers are one of the most competitive candidates for waveguide fabrication. In this work, we evaluate the performance of one example from each of three families of photopolymer material in fabrication of a 633nm waveguide. Firstly, polyvinyl alcohol acrylamide, PVA/AA, the second one, a nanoparticle-thiol-ene, NPC, and on the last place a penta/hexa-acrylate based polymer with dispersed nematic liquid crystal molecules, PDLC. We study the critical role of the material and in particular, spatial resolution for this application.

This work was supported by the “Ministerio de Ciencia, Innovacion y Universidades” (Spain) under projects FIS2017-82919-R (MINECO/AE/FEDER, UE) and FIS2015-66570-P (MINECO/FEDER). R.F. and M.M-V. acknowledge the financial support by the Generalitat Valenciana” (Spain) under grants APOSTD/2018/084 and CDEIGENT/2018/024, respectively.

In this work we present a non-destructive technique based on Fresnel diffraction to obtain the refractive index profile of a fiber grating. The system has been firstly calibrated by using the experimental data of the diffraction pattern of rectangular slits at different distances.

Financiado por Ministerio de Economia, Industria y Competitividad (Spain) con FIS2017-82919-R y FIS2015- 66570-P (MINECO/FEDER); Generalitat Valenciana (Spain) (PROMETEO II/2015/015).

In recent works, we demonstrated the accuracy and physical relevance of a highly simplified reverse-engineering analytical model for a parallel-aligned liquid crystal on silicon devices (PA-LCoS). Both experimental measurements and computational simulations applying the rigorous split-field finite difference time domain (SF-FDTD) technique led to this conclusion in the low applied voltages range. In this paper, we develop a complete rigorous validation covering the full range of possible applied voltages, including highly non-linear liquid crystal (LC) tilt angle profiles. We demonstrate the applicability of the model for spectral and angular retardation calculations, of interest in spatial light modulation applications. We also show that our analytical model enables the calculation of the retardance for novel PA-LC devices as a function of the LC compound and cell gap, becoming an appealing alternative to the usual numerical approaches for PA-LC devices design.

In this paper, we present a method to characterize a complete optical Holographic Data Storage System (HDSS), where we identify the elements that limit the capacity to register and restore the information introduced by means of a Liquid Cristal on Silicon (LCoS) microdisplay as the data pager. In the literature, it has been shown that LCoS exhibits an anamorphic and frequency dependent effect when periodic optical elements are addressed to LCoS microdisplays in diffractive optics applications. We tested whether this effect is still relevant in the application to HDSS, where non-periodic binary elements are applied, as it is the case in binary data pages codified by Binary Intensity Modulation (BIM). To test the limits in storage data density and in spatial bandwidth of the HDSS, we used anamorphic patterns with different resolutions. We analyzed the performance of the microdisplay in situ using figures of merit adapted to HDSS. A local characterization across the aperture of the system was also demonstrated with our proposed methodology, which results in an estimation of the illumination uniformity and the contrast generated by the LCoS. We show the extent of the increase in the Bit Error Rate (BER) when introducing a photopolymer as the recording material, thus all the important elements in a HDSS are considered in the characterization methodology demonstrated in this paper.

En este trabajo se muestran los resultados y conclusiones de la aplicacion de nuevos enfoques docentes en la imparticion de la asignatura Acustica en el Grado en Ingenieria en Sonido e Imagen en Telecomunicacion (GISIT). La investigacion docente realizada se ha basado en incluir nuevas mecanicas docentes: clase invertida, laboratorio virtual y actividades de gamificacion. El objetivo general de estas iniciativas ha sido la de mejorar la motivacion del alumnado, contribuir a realizar una docencia mas colaborativa y dinamica que sustituya la clase magistral convencional. Ademas, se han generado recursos que ayuden al alumnado a mejorar ciertas habilidades relacionadas con el laboratorio, y con la realizacion de pruebas tipo test. El laboratorio virtual, se ha disenado con el objetivo de crear una herramienta potente que permita simular una experiencia que es dificilmente realizable de forma practica e individual (o en grupos reducidos). La gamificacion se ha utilizado para ejercitar las cuestiones de tipo test con multiples opciones (mediante la actividad de un concurso tipo “?Quieres ser millonario?”). Finalmente, se ha elaborado y procesado una encuesta con el objeto de evaluar la percepcion de estas actividades por parte del alumnado. El resultado de este analisis muestra que de forma general el alumnado ha recibido de forma satisfactoria estas propuestas e incluso verian de forma positiva implantarlo al resto de la asignatura.

In this work, an accurate numerical modeling of the diffraction properties of transmission holographic polymer dispersed liquid crystal (H-PDLC) gratings is presented. The method considers ellipsoid geometry-based liquid crystal (LC) droplets with random properties regarding size and location across the H-PLDC layer and also the non-homogeneous orientation of the LC director within the droplet. The direction of the LC director inside the droplets can be varied to reproduce the effects of the external voltage applied in H-PDLC-based gratings. From the LC director distribution in the droplet, the permittivity tensor is defined, which establishes the optical anisotropy of the media, and it is used for numerically solving the light propagation through the system. In this work, the split-field finite-difference time-domain method (SF-FDTD) is applied. This method is suited for accurately analyzing periodic media, and it considers spatial and time discretisation of Maxwell's equations. The scheme proposed here is used to investigate the influence on the diffraction properties of H-PDLC as a function of the droplets size and the bulk fraction of LC dispersed material.

We propose some experiences, using spectrometric measurements, to show students how different media and different light sources have different behavior. We start by measuring several light sources with the help of a fiber optic spectrometer. This device allows us to demonstrate how different white-light sources can be distinguished by the wavelengths composing the source. In other words, we want to study the visible spectrum. Even monochromatic light sources, which have the same color when observed by the naked eye, can be characterized. With this experience, we want to study several materials by means of the measurements of the reflectance and transmittance. To do that, we propose the characterization of some light sources and the observation of how their spectra change when the light is transmitted or reflected by the material. It is important to remark how the fiber or propagation media can affect the source spectra. We show the method to characterize the light source in conjunction with the optic fiber. This experience is performed with students inside the unit entitled "Radiometry and Photometry" of the subject of "Fundamentals of Engineering Optics", basic subject included in the second course for obtaining a Degree in Telecommunication Engineering and "Optical Image Acquisition and Processing", from the Master in Automation and Robotics, both taught at the University of Alicante.

La evaluacion de las asignaturas en los grados, basados en el EEES, se realiza de forma continua en todas las asignaturas. Desde la puesta en marcha de los grados, la evaluacion continua ha sido criticada por la carga de Trabajo que representa tanto para el alumnado como el profesorado. Hace unos anos realizamos un proyecto colaborativo para la realizacion del Calendario de evaluacion continua por curso academico. Dicho calendario da una muestra de las evaluaciones y controles que se realizan en las asignaturas de cada curso y cada semestre, sin tener en cuenta las practicas. Sin embargo, las actividades de evaluacion han ido cambiando y en ocasiones no se detallan en la guia docente. Esto no permite realizar un calendario de evaluacion real del curso. El objetivo de este proyecto ha sido doble, por un lado coordinar todas las evaluaciones, controles, y actividades obligatorias o voluntarias de evaluacion en todas las asignaturas de cuarto curso del Grado de Telecomunicaciones de la Escuela Politecnica Superior (EPS) y por otro, la realizacion de un estudio mediante encuesta al alumnado para la obtencion de conclusiones sobre la planificacion de evaluacion continua que se esta realizando en el curso.

En este trabajo se recogen los resultados derivados de la aplicacion de nuevas metodologias docentes acompanadas de las Tecnologias de la Informacion y la Comunicacion (TIC). En particular se han incorporado actividades de docencia invertida, laboratorio virtual y gamificacion. Cada una de estas actividades se ha disenado para reforzar ciertos aspectos de la docencia que hasta la fecha presentaban deficiencias. Para evaluar la bonanza de estas actividades se ha elaborado una encuesta al alumnado donde se les pregunta sobre su percepcion ante todas estas propuestas metodologicas en la docencia de la asignatura.

En este trabajo de investigacion docente pretendemos actualizar los contenidos de la asignatura de Aislamiento y Acondicionamiento Acustico impartida en el tercer curso de la titulacion de Grado en Sonido en Imagen en Telecomunicacion para incluir la actualizaciones en la normativa ISO vigente que afectan a los contenidos de dicha asignatura de manera que el alumnado adquiera de forma correcta las competencias asignadas para esta materia y que contemplan estos aspectos. Ademas tambien se revisaran las practicas de la asignatura de Acustica para mejorar la calidad de la misma con el objetivo de mejorar aun mas si cabe la adquisicion de las competencias asignadas a esta parte de la asignatura y que resultan de vital importancia puesto que se trata de una asignatura fundamental en la titulacion de Grado en Sonido e Imagen en Telecomunicacion cuya compresion es basica para poder abordar con exito asignaturas de cursos posteriores basadas conceptos de acustica basicos.

En este articulo se describe el trabajo realizado por la red de investigacion en docencia universitaria denominada “Master en Ingenieria de Telecomunicacion: ?hacia la semipresencialidad?”. Se ha creado un grupo de trabajo conformado por todos los profesores responsables de asignaturas en el Master en Ingenieria de Telecomunicacion asi como por miembros de su Comision. Entre todos los miembros se ha estudiado como podrian impartirse las asignaturas de este master en modalidad semipresencial teniendo en cuenta el alto contenido cientifico-tecnico que presenta el master y muy especialmente algunas de sus asignaturas. Se han propuesto tres tipos de modalidad de imparticion semipresencial para las asignaturas, en las que podrian encuadrarse todas las asignaturas del master en funcion de si sus contenidos son mas descriptivos o con un mayor contenido matematico y/o fisico. Ademas, se ha realizado una encuesta al alumnado del master con el fin de conocer su opinion sobre una hipotetica semipresencialidad en la imparticion del master.

In this work, we present a method of manufacturing an optical see-through display based on a holographic waveguide with transmission holograms that couple the incident light between air and the glass substrate, accomplishing total internal reflection. The holograms (slanted transmission gratings with a spatial frequency of 1700 lines/mm) were recorded on a polyvinyl alcohol acrylamide (PVA/AA) photopolymer. We will also show that the addition of N,N′-methylene-bis-acrylamide (BMA) to the composition of the photopolymer allows the achievement of the index modulations necessary to obtain high diffraction efficiencies in non-slanted diffraction gratings of 1000 and 2200 lines/mm, and also in slanted gratings of 1700 lines/mm (which are the base of the optical system proposed).

The holographic storage of information is based on the interference of two waves: the reference wave and the object wave, the latter is generated by using a spatial light modulator, and in the case of applications of data storage this corresponds to a binary pattern of one and zeros. The interference pattern is recorded in a photosensitive medium (photopolymers, photographic emulsions, photorefractive, etc.), so that when illuminated by the reference wave the object wave is reproduced. In order to properly investigate the characteristics of the generated hologram it is necessary to adequately study the interaction of electromagnetic radiation with the recording medium. In this work we develop a completely vectorial formalism for solving the Helmholtz equation that allows investigation of electromagnetic dispersion in dielectric media in which the refractive index varies spatially. The method is based on the technique of Green's tensor and allows to correctly simulate the behavior of a volume hologram. This method is compared with the method of discrete dipoles and a formalism based on the first Born approximation to determine the intensity of light scattered by a volume hologram.