High-resolution optical frequency dissemination on a telecommunication network with data traffic

We transferred the frequency of an ultra-stable laser over a 108 km urban fiber link comprising 22 km of optical communications network fiber simultaneously carrying Internet data traffic. The metrological signal and the digital data signal are transferred on two different frequency channels in a dense wavelength division multiplexing scheme. The metrological signal is inserted into and extracted from the communications network by using bidirectional off-the-shelf optical add-drop multiplexers. The link-induced phase noise is measured and cancelled with round-trip technique using an all-fiber-based interferometer. The compensated link shows an Allan deviation of a few 10-16 at one second and below 10-19 at 10,000 seconds. This opens the way to a wide dissemination of ultra stable optical clock signals between distant laboratories via the Internet network

Labour Reallocation in Recession and Recovery:Evidence for Europe

This paper builds upon Bartelsman, Lopez-Garcia, and Presidente (2018) and provides empirical evidence on the cyclical features of labour reallocation in a sample of European Union (EU) countries over the Great Recession and the slow recovery. The analysis makes use of cross-country micro-aggregated data on firm dynamics and productivity from release 6 of the ECB CompNet database. While productivity-enhancing reallocation generally is counter-cyclical, with a stronger effect providing a silver lining in downturns, it was weaker during the Great Recession in the EU, but reverted back to more normal patters in the most recent years

Ultra-stable long distance optical frequency distribution using the Internet fiber network

We report an optical link of 540 km for ultrastable frequency distribution over the Internet fiber network. The stable frequency optical signal is processed enabling uninterrupted propagation on both directions. The robustness and the performance of the link are enhanced by a cost effective fully automated optoelectronic station. This device is able to coherently regenerate the return optical signal with a heterodyne optical phase locking of a low noise laser diode. Moreover the incoming signal polarization variation are tracked and processed in order to maintain beat note amplitudes within the operation range. Stable fibered optical interferometer enables optical detection of the link round trip phase signal. The phase-noise compensated link shows a fractional frequency instability in 10 Hz bandwidth of 5x10-15 at one second measurement time and 2x10-19 at 30 000 s. This work is a significant step towards a sustainable wide area ultrastable optical frequency distribution and comparison network

Digital FPGA Circuits Design for Real-Time Video Processing with Reference to Two Application Scenarios

In the present days of digital revolution, image and/or video processing has become a ubiquitous task: from mobile devices to special environments, the need for a real-time approach is everyday more and more evident. Whatever the reason, either for user experience in recreational or internet-based applications or for safety related timeliness in hard-real-time scenarios, the exploration of technologies and techniques which allow for this requirement to be satisfied is a crucial point. General purpose CPU or GPU software implementations of these applications are quite simple and widespread, but commonly do not allow high performance because of the high layering that separates high level languages and libraries, which enforce complicated procedures and algorithms, from the base architecture of the CPUs that offers only limited and basic (although rapidly executed) arithmetic operations. The most practised approach nowadays is based on the use of Very-Large-Scale Integrated (VLSI) digital electronic circuits. Field Programmable Gate Arrays (FPGAs) are integrated digital circuits designed to be configured after manufacturing, "on the field". They typically provide lower performance levels when compared to Application Specific Integrated Circuits (ASICs), but at a lower cost, especially when dealing with limited production volumes. Of course, on-the-field programmability itself (and re-programmability, in the vast majority of cases) is also a characteristic feature that makes FPGA more suitable for applications with changing specifications where an update of capabilities may be a desirable benefit. Moreover, the time needed to fulfill the design cycle for FPGA-based circuits (including of course testing and debug speed) is much reduced when compared to the design flow and time-to-market of ASICs. In this thesis work, we will see (Chapter 1) some common problems and strategies involved with the use of FPGAs and FPGA-based systems for Real Time Image Processing and Real Time Video Processing (in the following alsoindicated interchangeably with the acronym RTVP); we will then focus, in particular, on two applications. Firstly, Chapter 2 will cover the implementation of a novel algorithm for Visual Search, known as CDVS, which has been recently standardised as part of the MPEG-7 standard. Visual search is an emerging field in mobile applications which is rapidly becoming ubiquitous. However, typically, algorithms for this kind of applications are connected with a high leverage on computational power and complex elaborations: as a consequence, implementation efficiency is a crucial point, and this generally results in the need for custom designed hardware. Chapter 3 will cover the implementation of an algorithm for the compression of hyperspectral images which is bit-true compatible with the CCSDS-123.0 standard algorithm. Hyperspectral images are three dimensional matrices in which each 2D plane represents the image, as captured by the sensor, in a given spectral band: their size may range from several millions of pixels up to billions of pixels. Typical scenarios of use of hyperspectral images include airborne and satellite-borne remote sensing. As a consequence, major concerns are the limitedness of both processing power and communication links bandwidth: thus, a proper compression algorithm, as well as the efficiency of its implementation, is crucial. In both cases we will first of all examine the scope of the work with reference to current state-of-the-art. We will then see the proposed implementations in their main characteristics and, to conclude, we will consider the primary experimental results

Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference

We have built a frequency chain which enables to measure the absolute frequency of a laser emitting in the 28-31 THz frequency range and stabilized onto a molecular absorption line. The set-up uses an optical frequency comb and an ultrastable 1.55 $\mu$m frequency reference signal, transferred from LNE-SYRTE to LPL through an optical link. We are now progressing towards the stabilization of the mid-IR laser via the frequency comb and the extension of this technique to quantum cascade lasers. Such a development is very challenging for ultrahigh resolution molecular spectroscopy and fundamental tests of physics with molecules

Cascaded multiplexed optical link on a telecommunication network for frequency dissemination

We demonstrate a cascaded optical link for ultrastable frequency dissemination comprised of two compensated links of 150 km and a repeater station. Each link includes 114 km of Internet fiber simultaneously carrying data traffic through a dense wavelength division multiplexing technology, and passes through two routing centers of the telecommunication network. The optical reference signal is inserted in and extracted from the communication network using bidirectional optical add-drop multiplexers. The repeater station operates autonomously ensuring noise compensation on the two links and the ultra-stable signal optical regeneration. The compensated link shows a fractional frequency instability of 3 \times 10-15 at one second measurement time and 5 \times 10-20 at 20 hours. This work paves the way to a wide dissemination of ultra-stable optical clock signals between distant laboratories via the Internet network

Audiovisual resources as a useful tool to improve the teaching of coastal engineering (marine science bsc degree)

Numerous graduates from American Universities apply for their degree homologation for the Marine Science certificate in Spain. The Spanish Ministry of Education supports this as long as they can pass an exam based on several subjects including Coastal Engineering at the University of Cadiz. The subject of Coastal Engineering is currently being taught in the third year of the BSc degree. This is a very specific subject and unfortunately there is no adequate bibliography that allows for the breadth of knowledge needed to pass the final exam. In addition, it may be difficult for foreign students to properly prepare the subject because they cannot attend the lessons at the campus. Therefore, an innovative project was proposed to create videos where lessons are explained. These files were uploaded to the Virtual Classroom. In this way, students of the Marine Science BSc degree were also encouraged to use these audiovisual resources because not all of the enrolled students were able to attend the classes as they had clashing schedules. On the other hand, some students have an Erasmus grant and their knowledge of Spanish has not reached the required level in terms of assimilating all the given explanations. Enabling these audiovisual resources would be very useful for their studies, not only from a technical but also from a linguistic point of view. The exams from the last few years were solved and explained in documents that were also uploaded later to the Virtual Classroom in order to facilitate the study of the subject. This represented a valid and helpful alternative way in which students could prepare for their final exam. During the months of September and October a grantee was hired to assist the preparation of all the teaching material. From November to January, several PowerPoint files were prepared (including formulations, summaries and practical solved exercises) and oral explanations were implemented. The performance of the audiovisual resources was facilitated by the free software Active Presenter (http://atomisystems.com/activepresenter/). The students completed a satisfaction survey about the quality and usefulness of the audiovisual lectures, in order to assess the levels of interest and success that were achieved. According to the results obtained, these audiovisual resources can be considered to be in the public domain and hence can be uploaded to the Cadiz University repository. In order to disseminate the results of the project’s usefulness in academia, lectures explaining its methodology, results and conclusions used will be given, not only in the same faculty but also at this International Conference to further its applications to other subjects

First Workshop on Identification of Future Emerging Technologies for Low Carbon Energy Supply

As part of the European Commission's internal Low Carbon Energy Observatory project, the Joint Research Centre is developing an inventory of future emerging technologies relevant to energy supply. A key part of this initiative is consultation with external experts. This workshop is the first step in this process. It targets two main energy research areas: electricity from electromagnetic irradiation (principally photovoltaics, but also thermo-electric concepts) and fuels (comprising fuel cells, hydrogen and biofuels). Issues of general interest are also considered. The goal is to identify innovative technologies and processes for energy supply, possibly not sufficiently considered in current research funding programs.JRC.C.4-Sustainable Transpor

Tackling the Limits of Optical Fiber Links

International audienceWe theoretically and experimentally investigate relevant noise processes arising in optical fiber links, which fundamentally limit their relative stability. We derive the unsuppressed delay noise for three configurations of optical links: two-way method, Sagnac interferometry, and actively compensated link, respectively designed for frequency comparison, rotation sensing, and frequency transfer. We also consider an alternative two-way setup allowing real-time frequency comparison and demonstrate its effectiveness on a proof-of-principle experiment with a 25-km fiber spool. For these three configurations, we analyze the noise arising from uncommon fiber paths in the interferometric ensemble and design optimized interferometers. We demonstrate interferometers with very low temperature sensitivity of respectively -2.2, -0.03 and 1 fs/K. We use one of these optimized interferometers on a long haul compensated fiber link of 540 km. We obtain a relative frequency stability of 3x10^-20 after 10,000 s of integration time