1,720,956 research outputs found
Ultralow loss and wide bandwidth hollow-core photonic bandgap fibres for telecom applications
No full textLight guidance in air has significant potential in diverse photonics applications, one of hich is optical communications where it may be key to achieving lower attenuation and optical nonlinearity than in conventional silica fibres. This thesis presents research conducted as part of the EU FP7 project MODEGAP, and is concerned with the design of hollow-core photonic bandgap fibres (HC-PBGFs) with low loss and wide bandwidths suitable for high capacity data transmission.In these fibres, loss is dominated by scattering from surface roughness and is subject to the design of the fibre cross-section. Using the criterion of reduced guided mode-field intensity at the interfaces, we conduct detailed finite element simulations which allow to identify preferable structures. A theory of light scattering from surface roughness in HC-PBGFs is then derived, and expressions are obtained which combine statistical information on the roughness and the guided mode-field overlap with scattering surfaces to predict the far-field scattering pattern and the fibre loss.A model based on mass conservation is proposed to predict the properties of HC-PBGFs from knowledge of the preforms from which they are made, and this in turn allows optimizing the design of such preforms. A method allowing accurate modelling of fabricated HC-PBGFs from scanning electron micrographs of their cross-sections is devised and such simulations indicate that structural distortions in the fibre cross-section cause higher field intensities near the interfaces, and hence higher losses. Systematic studies of distortions are then conducted, and it is found that not all distortions are equally detrimental. Combining these findings and using realistic estimates, a HC-PBGF design with 37 cell core defect and loss as low as 0.2dB/km over 580nm of bandwidth near the wavelength of 2µm is presented
Dataset for 'The Thermal Phase Sensitivity of both Coated and Uncoated Standard and Hollow Core Fibers down to Cryogenic Temperatures'
No full textThis dataset supports the publication:
Zhu, Wenwu ; Numkam Fokoua, Eric Rodrigue ; Taranta, Austin ; Chen, Yong ; Bradley, Thomas ; Petrovich, Marco ; Poletti, Francesco ; Zhao, Mingshan ; Richardson, David ; Slavík, Radan. / The Thermal Phase Sensitivity of both Coated and Uncoated Standard and Hollow Core Fibers down to Cryogenic Temperatures. In: IEEE Journal of Lightwave Technology. 2019</span
Dataset for "Temperature-insensitive delay-line fiber interferometer operating at room temperature"
No full textData to support the article "Temperature-insensitive delay-line fiber interferometer operating at room temperature" Published in the Journal of Lightwave Technology
The dataset consists of an Uploaded Archive (RAR) containing 6 data files that are Excel format (.xlsx)
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Dataset for article: 'Backscattering in antiresonant hollow-core fibers: over 40 dB lower than in standard optical fibers'
No full textDataset for data presented in article.V. MICHAUD-BELLEAU, E.R. NUMKAM FOKOUA, T.D. BRADLEY, J.R. HAYES,Y. CHEN, F. POLETTI, D.J. RICHARDSON, J. GENEST, AND R. SLAVIK. Backscattering in antiresonant hollow-core fibers: over 40 dB lower than in standard optical fibers, Optica 2021. Includes 21 data files that are purely numerical (.txt)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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