Síntesis y caracterización de vidrios, vitrocerámicos, y vidrios en lámina delgadas de fluoroteluritos dopados con tierras raras para aplicaciones fotónicas activas

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de Materiales. Fecha de lectura: 02-07-201

Subtle local structural variations in oxygen deficient niobium germanate thin film glasses as revealed by x-ray absorption spectroscopy

6 págs.; 4 figs.; 2 tabs. 16th International Conference on X-ray Absorption Fine Structure (XAFS16) ; Open Access funded by Creative Commons Atribution Licence 3.0The local electronic and crystal structure of niobium-lead-germanate, Nb2O5-PbO- GeO2 (NPG), glass thin films on silicon substrates were probed by XANES and EXAFS. NPG glasses are promising candidates for applications in nonlinear optical devices because they exhibit interesting optical characteristics such as high nonlinear third order optical susceptibility. In this work NPG glasses were prepared with pulsed laser deposition method with varying oxygen partial pressure to induce thin films with different oxygen stoichiometry. Previously, it was shown that oxygen stoichiometry has a very important effect to produce unusual high optical susceptibility. Detailed EXAFS and XANES analyses in a series of NPG thin films revealed the subtle variations in the local environment around Nb atoms and the Nb oxidation states caused by oxygen deficiencies. Published under licence by IOP Publishing LtdPeer Reviewe

Er3+-doped fluorotellurite thin film glasses with improved photoluminescence emission at 1.53 µm

7 págs.; 5 figs.; 4 tabs.Transparent oxyfluoride tellurite thin film glasses have been produced at room temperature by pulsed laser deposition in O2 atmosphere from an Er-doped TeO2–ZnO–ZnF2 bulk glass. Thin film glasses present high refractive index (n≥1.95) and good transparency (T≥80%) in the visible (λ>400 nm) and near infrared range. However, their photoluminescence (PL) performance at 1.5 μm is poor. Thermal annealing at moderate temperatures (T≤315 °C), well below glass crystallization, increases the PL intensity by more than one order of magnitude as well as the PL lifetime up to τ≈3.3 ms. Film glasses present a larger fraction of TeO3 trigonal pyramids than the bulk glass and a very large OH− content. The structure and composition of film glasses do not change upon annealing and thus the activation of the PL response is related to the improvement of the surface morphology and the significant decrease of their OH− content. & 2015ElsevierB.V.This work has been supported by the Spanish Government (Projects MAT2009-14282-C02-01, MAT2009-14282-C02-02, TEC 2012-38901-C02-01, MAT2013-48246-C2-2-P and FIS2013-48087-C2-1-P).Peer Reviewe

Mid IR emission from highly transparent Er3+ doped tellurite glass ce- ramic for bio applications

Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, San Jose, California, USA, 08 - 13 Jun 2014Intense emission peaking at 2.18 ¿m was successfully obtained from erbium upon rigorous engineering of its glass host. Highly localized crystallization of erbium sites is substantiated by micro Raman and micro-PL along with TEM.Peer Reviewe

Active mid-IR emissions from rare-earth doped tellurite glass ceramics for bioapplications

16th International Conference on Transparent Optical Networks, Graz (Grazer Messe), Austria, July 6th - 10th, 2014.Promising bio based applications such as bloodless surgery, non-invasive blood constituents monitoring or high sensitivity tracing of green house gases could be designed starting form optically active materials working within the 2.0-2.3 μm wavelength window. For this purpose, room temperature operated high power devices are entering the market of which rare-earth (RE) doped devices hold a prominent place. But such devices are based today on 3+ rare-earth doping of thulium and holmium. Though Er has an active 2.0 μm transition to achieve broad emission bandwidth, it is usually quenched in an amorphous matrix and hence rarely reported in glasses or any other 3+ as the active ion backbone would leverage efforts and investments done in the telecom industry to non-telecom applications which would allow a quick progression. This work successfully reports the engineering of the base glass matrix to produce the key 2.0 μm emission. This was obtained by specific selection of precursors and custom-designed heat treatment of an Er doped fluorotellurite glass.This work has been supported by the Spanish Ministry of Economy and Competitiveness (Projects TEC2011-22422, FIS2011-27968 and TEC2012-38901-C02-01)Peer Reviewe

Descubriendo la Luz: acercando la óptica a la sociedad

XIII Reunión Nacional de Óptica. -- Evento online, 22-24 noviembre 2021Peer reviewe

Discovering Light: Fun Experiments with Optics

Editor(s): Maria Viñas-Peña.Light is an element that draws together many areas of human knowledge: physics, chemistry, biology, astronomy, engineering, and art. Moreover, optical phenomena and the technologies based on them are widespread in our daily lives. However, it can be difficult to understand or explain these phenomena. What is light? Where are optics and photonics present in our lives and in nature? What lies behind different optical phenomena? What is an optical instrument? How does the eye resemble an optical instrument? How can we explain human vision? This book, written by a group of young scientists, answers these questions and many more to help you to get to know the exciting world of optics and photonics. It is intended for the general public, with an emphasis on students at all levels of secondary education. A variety of easy-to-follow experiments related to different optical phenomena and technologies are presented. All of them are preceded by an explanation of the concepts and accompanied by numerous illustrations and curiosities. All of it is meant for you to have fun with optics and photonics!Peer reviewe

Acute Delta Hepatitis in Italy spanning three decades (1991–2019): Evidence for the effectiveness of the hepatitis B vaccination campaign

Updated incidence data of acute Delta virus hepatitis (HDV) are lacking worldwide. Our aim was to evaluate incidence of and risk factors for acute HDV in Italy after the introduction of the compulsory vaccination against hepatitis B virus (HBV) in 1991. Data were obtained from the National Surveillance System of acute viral hepatitis (SEIEVA). Independent predictors of HDV were assessed by logistic-regression analysis. The incidence of acute HDV per 1-million population declined from 3.2 cases in 1987 to 0.04 in 2019, parallel to that of acute HBV per 100,000 from 10.0 to 0.39 cases during the same period. The median age of cases increased from 27 years in the decade 1991-1999 to 44 years in the decade 2010-2019 (p < .001). Over the same period, the male/female ratio decreased from 3.8 to 2.1, the proportion of coinfections increased from 55% to 75% (p = .003) and that of HBsAg positive acute hepatitis tested for by IgM anti-HDV linearly decreased from 50.1% to 34.1% (p < .001). People born abroad accounted for 24.6% of cases in 2004-2010 and 32.1% in 2011-2019. In the period 2010-2019, risky sexual behaviour (O.R. 4.2; 95%CI: 1.4-12.8) was the sole independent predictor of acute HDV; conversely intravenous drug use was no longer associated (O.R. 1.25; 95%CI: 0.15-10.22) with this. In conclusion, HBV vaccination was an effective measure to control acute HDV. Intravenous drug use is no longer an efficient mode of HDV spread. Testing for IgM-anti HDV is a grey area requiring alert. Acute HDV in foreigners should be monitored in the years to come

Brain energy rescue:an emerging therapeutic concept for neurodegenerative disorders of ageing

The brain requires a continuous supply of energy in the form of ATP, most of which is produced from glucose by oxidative phosphorylation in mitochondria, complemented by aerobic glycolysis in the cytoplasm. When glucose levels are limited, ketone bodies generated in the liver and lactate derived from exercising skeletal muscle can also become important energy substrates for the brain. In neurodegenerative disorders of ageing, brain glucose metabolism deteriorates in a progressive, region-specific and disease-specific manner — a problem that is best characterized in Alzheimer disease, where it begins presymptomatically. This Review discusses the status and prospects of therapeutic strategies for countering neurodegenerative disorders of ageing by improving, preserving or rescuing brain energetics. The approaches described include restoring oxidative phosphorylation and glycolysis, increasing insulin sensitivity, correcting mitochondrial dysfunction, ketone-based interventions, acting via hormones that modulate cerebral energetics, RNA therapeutics and complementary multimodal lifestyle changes

Luminescence of Er3+ ions in nanocrystalline glass-ceramics

Part of the NATO Science for Peace and Security Series B: Physics and Biophysics book series (NAPSB)This work analyzes the influence of the nanocrystals on the luminescence properties of Er3+ions in transparent oxyfluoride tellurite glass-ceramics obtained by heat treatment of the precursor Er-doped glass. The comparison between the fluorescence properties of Er-doped glass and glass-ceramic suggests that a fraction of Er3+ ions are forming nanocrystals while the rest remain in a glass environment. The presence of ErF3 nanocrystals has a strong effect in the upconverted red emission from4F9/2 level. The time evolution of the upconverted red emission shows that energy transfer upconversion processes are responsible for the increase of this emission in the glass-ceramic sample.We deeply acknowledge A. Tomas from the National Centre for Metallurgical Research (CENIM, CSIC) and A. Ruiz-Caridad from the Laboratory of Electron Nanoscopies (LENS, University of Barcelona) for TEM sample preparation and HRTEM analysis, respectively. This work was supported by the Spanish Government MEC under Projects No. TEC2012-38901-C02-01 and MAT2013-48246-C2-2-P and Basque Country Government IT-659-13 and IT-943-16. R. Morea acknowledge a FPI grant from the Spanish Government (BES-2010-038084).Peer Reviewe