El campus virtual y la adecuación a los créditos ECTS

La integración del sistema universitario español en el Espacio Europeo de Educación Superior (EEES) implica la aceptación de un nuevo modelo educativo basado en el trabajo y en el aprendizaje del alumnado. Por tanto, la importancia de la docencia directa por parte del profesorado se reduce considerablemente ampliando su dedicación a organizar, orientar y supervisar el trabajo del alumnado. Las nuevas tecnologías serán importantes en el EEES ya que fomentarán la realización de tareas de aprendizaje deslocalizadas y en un marco horario más flexible que el actual. Cualquier aspecto docente es susceptible de integrarse en el entorno del campus virtual de la Universidad de Alicante (CVUA). Sin embargo, el éxito o fracaso de esta reforma estará en función de que, por una parte, el alumnado asuma el papel activo que le concede el nuevo modelo educativo y de que, por otra, la administración dote de los recursos necesarios para llevar a cabo este proceso. En esta contribución presentamos un conjunto de actividades, implementadas en el CVUA, que permitirán adecuar nuestras asignaturas a la estructura de los créditos europeos. El profesorado que compone el grupo de trabajo ha desarrollado acciones docentes encaminadas a la adaptación de las asignaturas al sistema de créditos europeos.SIN FINANCIACIÓNNo data 200

Depth attenuated refractive index profiles in holographic gratings recorded in photopolymer materials

Photopolymers are systems of organic molecules that rely on photoinitiated polymerization to record volume phase holograms. Characteristics such as good light sensitivity, large dynamic range, good optical properties and relatively low cost make photopolymers one of the most promising materials for write-one, read-many (WORM) holographic data storage applications. Thus, it is interesting to understand the mechanisms that control the way information is stored in photopolymer materials. Different authors have demonstrated that two processes play the main role in hologram formation: monomer polymerization and monomer diffusion. A number of models based on these two processes have been proposed and their prediction capability has been validated. In this work we extend the capabilities of the existent models by introducing another important characteristic: the attenuation of light through the depth of the material which happens in the recording process. In order to check the validity of the theoretical model that we propose, volume phase transmission gratings are recorded in a PVA/Acrylamide photopolymer with different spatial frequencies. Using the Rigorous Coupled Wave Theory (RCWT) we show that we can obtain information about the higher harmonics in the recorded refractive index modulation. Comparison between simulated and experimental results validates the interpretation provided by the proposed model.This work was supported by the "Ministerio de Ciencia y Tecnología", CICYT, Spain, under project MAT2000-1361-C04-04

Effect of the glass substrate on the efficiency of the different orders that propagate in a transmission sinusoidal diffraction grating

In this work we study the effect of the glass substrate on the efficiencies of the different orders that propagate inside a transmission sinusoidal diffraction grating. Holographic optical elements are usually recorded on a photosensitive medium deposited on to a glass substrate. Therefore, the study of the entire system, namely the holographic element plus the glass substrate, is necessary. In this work we study the entire system by using the rigorous coupled-wave theory. As will be demonstrated, the effect of the glass is to generate an oscillatory pattern of the efficiency of the different orders around the average. The effect of the glass substrate is therefore sufficiently significant, and care must be taken in order to choose the appropriate thickness of the glass if maximum diffraction efficiency is to be achieved.This work was supported by the Ministerio de Educación y Ciencia, Spain, under projects FIS2005-05881-C02-02 and FIS2005-05881-C02-01 and with the help of Alicante University under project GRE04-16

3-D behaviour of photopolymers as holographic recording material

Research dealing with models to predict and understand the behaviour of photopolymers have generated many interesting studies considering a 2-dimensional geometry. These models suppose that the photopolymer layer is homogeneous in depth. Using this approximation good results can be obtained if the thickness of photopolymers is less than 200 μm. However, it is well known that Lambert-Beer's law predicts an exponential decay of the light inside the material. In recent years intensive efforts have been made to develop new holographic memories based on photopolymers. For this application the thickness of the layer is increased, usually to more than 500 μm, and Lambert-Beer's law plays a significant role in the recording step. The attenuation of the index profile inside these materials has been measured, showing that it is an important phenomenon. This attenuation limits the maximum effective optical thickness of the grating and shows that the 2-D models can not be applied in these cases. For this reason in this work a 3-dimensional model is presented to analyze the real behaviour of the photopolymers and study the variations in the index profile in depth. In this work we examine the predictions of the model in the case of a general dependence of the polymerisation rate with respect to the intensity pattern, and the effects of varying the exposure intensity are also compared in 3-D cases. Finally, the limitation of the data storage capacity of the materials due to the Lambert-Beer law is evaluated.This work was supported by "Oficina de Ciencia y Tecnología, Generalitat Valenciana, Spain under projects GV01-130, GV04A/574 and GV04A/565, by "Ministerio de Educación y Ciencia", Spain, under projects MAT2004-04881-C02-01 and MAT2004-04881-C02-01, and by Science Foundation of Ireland (SFI), Enterprise, Ireland