Distributed Raman optical amplification in phase coherent transfer of optical frequencies

We describe the application of Raman Optical-fiber Amplification (ROA) for the phase coherent transfer of optical frequencies in an optical fiber link. ROA uses the transmission fiber itself as a gain medium for bi-directional coherent amplification. In a test setup we evaluated the ROA in terms of on-off gain, signal-to-noise ratio, and phase noise added to the carrier. We transferred a laser frequency in a 200 km optical fiber link with an additional 16 dB fixed attenuator (equivalent to 275 km of fiber on a single span), and evaluated both co-propagating and counter-propagating amplification pump schemes, demonstrating nonlinear effects limiting the co-propagating pump configuration. The frequency at the remote end has a fractional frequency instability of 3e-19 over 1000 s with the optical fiber link noise compensation

Le fallacie argomentative tra logica e dialettica

This paper is about the so-called fallacies of reasoning, that is, those arguments that seem to be compelling but don’t. It is argued that, strictly speaking, the traditional distinction between formal and pragmatic fallacies is impossible. However, another distinction, here proposed, between origin and import of fallacies turns out to be useful for classificatory purposes. The origin of a fallacy is that property on which the fallacious character of an argument ultimately depends. That property is the same in all contexts in which the fallacy can take place. By contrast, the import of a fallacy is the set of consequences that it typically has in each context. Identifying the origin of fallacies not always is a simple undertaking. In that regard, petitio principii presents special difficulties. It will be offered a detailed critique of the traditional analysis of petitio principii. This critique is aimed at showing that there are two distinct fallacies, both called petitio principii in the literature, erroneously considered as identical. It will be shown that one of these fallacies, which occurs only in the context of axiomatic proof, is a special case of non sequitur fallacy. By contrast, the other fallacy, which occurs typically in the dialectical context, derives from the fact that the credibility of a proposition cannot grow through a circular argument. A Bayesian analysis of this fact is proposed

Teletándem y CORINÉI: las nuevas tecnologías para el aula de I/LE en la UA

De la colaboración entre UA, UNISOB y UNISA nace en 2009 un proyecto de teletándem entre estudiantes de IL/E y EL/E para ejercitar la interacción oral entre hablantes nativos (HN) y no nativos (HNN). Cada universidad adapta esa actividad a sus respectivos programas docentes que, en la UA en el grado en Traducción e Interpretación, se integra como tarea fuera del aula aportando contenido a prácticas reconocidas en las guías docentes de los cursos: trabajo dirigido y evaluación de la lengua oral (la producción conversacional “HNN/HN” sustituye al clásico examen “discente/docente”). El objetivo final de la tarea, colaborativa y evaluable, pretende ofrecer al discente la oportunidad de interaccionar con nativos a través de las TICs, enfrentarse a problemas de carácter pragmático y sociolingüístico en conversación espontánea, reflexionar sobre aspectos metalingüísticos y tomar conciencia del propio proceso de enseñanza/aprendizaje. El material producido (HNN/HN), clasificado y en proceso de digitalización, configura un corpus de interlengua oral español/italiano (CORINÉI), dirigido a la investigación y la metodología contrastiva de estas lenguas afines. En el póster que proponemos ilustraremos las aportaciones de Teletándem y CORINÉI en calidad de herramientas de trabajo didácticas en I/LE impartida en la UA y presentaremos la página web que las alojará

Frequency transfer via a two-way optical phase comparison on a multiplexed fiber network

We performed a two-way remote optical phase comparison on optical fiber. Two optical frequency signals were launched in opposite directions in an optical fiber and their phases were simultaneously measured at the other end. In this technique, the fiber noise was passively cancelled, and we compared two optical frequencies at the ultimate 1E-21 stability level. The experiment was performed on a 47 km fiber that is part of the metropolitan network for Internet traffic. The technique relies on the synchronous measurement of the optical phases at the two ends of the link, that is made possible by the use of digital electronics. This scheme offers several advantages with respect to active noise cancellation, and can be upgraded to perform more complex tasks

Planar-Waveguide External Cavity Laser Stabilization for an Optical Link with 1E-19 Frequency Stability

We stabilized the frequency of a compact planar-waveguide external cavity laser (ECL) on a Fabry-P\'erot cavity (FPC) through a Pound-Drever-Hall scheme. The residual frequency stability of the ECL is 1E-14, comparable to the stability achievable with a fiber laser (FL) locked to a FPC through the same scheme. We set up an optical link of 100 km, based on fiber spools, that reaches 1E-19 relative stability, and we show that its performances using the ECL or FL are comparable. Thus ECLs could serve as an excellent replacement for FLs in optical links where cost-effectiveness and robustness are important considerations

effect of a timebase mismatch in two way optical frequency transfer

Two-way frequency transfer on optical fibers is a powerful technique for the comparison of distant clocks over long and ultra-long hauls. In contrast to traditional Doppler noise cancellation, it is capable of sustaining higher link attenuation, mitigating the need of optical amplification and regeneration and thus reducing the setup complexity. We investigate the ultimate limitations of the two-way approach on a 300 km multiplexed fiber haul, considering fully independent setups and acquisition systems at the two link ends. We derive a theoretical model to predict the performance deterioration due to a bad synchronisation of the measurements, which is confirmed by experimental results. This study demonstrates that two-way optical frequency transfer is a reliable and performing technique, capable of sustaining remote clocks comparisons at the resolution, and is relevant for the development of a fiber network of continental scale for frequency metrology in Europe

Italiano para la traducción: corpus interlengua y materiales docentes

La comunicación que proponemos tiene su origen en los resultados de la red docente que estamos desarrollando durante el curso 2015-2016 que lleva por título "Creación de materiales didácticos orales para la clase de lengua para la traducción". A partir de la experiencia de proyecto colaborativo realizada en los últimos cinco años por los alumnos de I/LE del grado en Traducción e Interpretación de la Universidad de Alicante que pone en práctica la interacción oral con hablantes italianos nativos de UNISA y UNISOB, el equipo de profesores de italiano que participan en la red ha desarrollado una serie de materiales docentes, fruto del análisis de una selección de conversaciones del corpus CORINÉI, que pretenden introducir mejoras en el proceso de enseñanza/aprendizaje de los actuales y futuros alumnos del grado, gracias a la información que nos aportan esas prácticas de interacción ya evaluadas

In-field entanglement distribution over a 96 km-long submarine optical fibre

Techniques for the distribution of quantum-secured cryptographic keys have reached a level of maturity allowing them to be implemented in all kinds of environments, away from any form of laboratory infrastructure. Here, we detail the distribution of entanglement between Malta and Sicily over a 96 km-long submarine telecommunications optical fibre cable. We used this standard telecommunications fibre as a quantum channel to distribute polarisation-entangled photons and were able to observe around 257 photon pairs per second, with a polarisation visibility above 90%. Our experiment demonstrates the feasibility of using deployed submarine telecommunications optical fibres as long-distance quantum channels for polarisation-entangled photons. This opens up a plethora of possibilities for future experiments and technological applications using existing infrastructure.Comment: 6 pages, 4 figure