1,721,078 research outputs found
Dataset for Temperature insensitive fiber interferometry
No full textData supporting the paper Zhu, Wenwu ; Numkam Fokoua, Eric ; Chen, Yong ; Bradley, Thomas ; Petrovich, Marco ; Poletti, Francesco ; Zhao, Mingshan ; Richardson, David ; Slavík, Radan. / Temperature insensitive fiber interferometry. In: Optics Letters. 2019</span
Do we need anything other than the C-band?
No full textSingle-mode silica fibers and erbium doped fiber amplifiers have been the cornerstone of optical communications for decades, but they are now approaching fundamental limits. This workshop aims to look well beyond the immediate short-term horizon and will discuss the need for and potential of more radically new forms of optical fibers and amplifiers.The workshop will bring together fiber and amplifier end-users and manufacturers, glass scientists and network operators to exchange views on the projected requirements for future communications systems and on the anticipated capabilities of alternative fiber and amplifier technologies. Is a gradual evolution of the current technology still possible or is a revolution required at some point? Are there potentially breakthrough technologies that could enable radical cost savings and energy efficient capacity growth? What if not? Blue sky thinking will be actively encouraged.Workshop organizers: Francesco Poletti, University of Southampton, UKOleg V. Sinkin, TE SubCom, USASpeakers:Part I:David DiGiovanni, OFS, USARené-Jean Essiambre, Nokia, USADavid Payne, University of Southampton, UKTim Stuch, Microsoft, USASergey Ten, Corning, USAPart II:John Ballato, Clemson University, USAEvgeny Dianov, General Physics Institute, RussiaYasuhiro Koike, Keio University, JapanMarco Petrovich, University of Southampton, UK</b
Gallium lanthanum sulphide glasses for near-infrared photonic applications
No full textThis thesis investigates gallium lanthanum oxysulphide (GLS) glasses for potential fibre device applications. GLS glasses have low phonon energy and high rare earth solubility, which makes them candidates for rare earth-doped devices, and in particular for the 1.3 µm praseodymium-doped optical fibre amplifier. In addition, they have one of the highest nonlinear figures of merit among optical glasses, and therefore have potential for all-optical switching and other nonlinear devices. Practical applications, however, have been prevented by the impossibility, to date, of achieving single mode fibres with low attenuation. Previous efforts were concentrated on fabrication and especially tried to address the known issues of glass purity and thermal stability. The present work is focussed on assessing the fundamental glass transparency and on the mechanisms affecting the transmission loss of GLS glasses. The optical absorption at 1.55 and 1.7 µm was measured for the first time by laser absorption calorimetry using a tunable free electron laser source. To this end, a calorimeter was designed and commissioned and an improved model for the heat flow analysis of laser calorimetry was also developed. Our measurements identified optical absorption as the principal near-IR loss mechanism for GLS glasses. The extrinsic absorption due to transition metal ion impurities was also measured, and the presence of the weak absorption tail, due to absorption from gap states, was investigated. The occurrence of photoinduced effects and their impact on the material's transmission was also analysed. A thorough characterisation of the photodarkening and photoinduced absorption due to bandgap illumination, including its dependence on the excitation wavelength, and the kinetics of its formation, decay and reversibility, was achieved. Finally, the response of GLS glasses to high-intensity irradiation in the 1 µm wavelength region was studied and photoinduced darkening was observed to occur in low oxide undoped and Pr3+-doped GLS. All these topics are of great practical relevance. The present work clearly demonstrates that, in addition to the known fabrication challenges of monomode GLS fibres, careful consideration of the intrinsic transparency and photoinduced effects is essential for their successful application in fibre devices
Fiber-optic sensors: optical fibers
No full textHandbook of Optical Sensors provides a comprehensive and integrated view of optical sensors, addressing the fundamentals, structures, technologies, applications, and future perspectives. Featuring chapters authored by recognized experts and major contributors to the field, this essential reference:* Explains the basic aspects of optical sensors and the principles of optical metrology, presenting a brief historical review* Explores the role of optical waveguides in sensing and discusses sensor technologies based on intensity and phase modulation, fluorescence, and plasmonic waves* Describes wavefront sensing, multiphoton microscopy, and imaging based on optical coherence tomography* Covers optical fiber sensing, from light guiding in standard and microstructured optical fibers to sensor multiplexing, distributed sensing, and fiber Bragg grating* Offers a broad perspective of the field and identifies trends that could shape the future, such as metamaterials and entangled quantum states of light
Hollow-core photonic bandgap fibers: technology and applications
No full textSince the early conceptual and practical demonstrations in the late 1990s, Hollow-Core Photonic Band Gap Fibres (HC-PBGFs) have attracted huge interest by virtue of their promise to deliver a unique range of optical properties that are simply not possible in conventional fibre types. HC-PBGFs have the potential to overcome some of the fundamental limitations of solid fibres promising, for example, reduced transmission loss, lower nonlinearity, higher damage thresholds and lower latency, amongst others. They also provide a unique medium for a range of light: matter interactions of various forms, particularly for gaseous media. In this paper we review the current status of the field, including the latest developments in the understanding of the basic guidance mechanisms in these fibres and the unique properties they can exhibit. We also review the latest advances in terms of fibre fabrication and characterisation, before describing some of the most important applications of the technology, focusing in particular on their use in gas-based fibre optics and in optical communications
Fibre‐Optic Sensing
No full textThis chapter reflects upon the past and on the achievements that fibre sensors have made over the past half-century. It explains the simple observation that market presence of fibre-optic sensing is modest at best. The chapter illustrates the essentials of a photonic system. Photonics as a discipline is most certainly arousing strategic interest with targeted research and development programmes emerging in both the United States and the European Union. The microstructured fibres, also known as photonic crystal fibres, dramatically increased the variety of geometries and optical responses available to fibre-based sensing. These fibres have arrays of wavelength-scale air holes in their transverse cross section, which extend along the full fibre length and define the waveguide properties. Fibre-optic sensing will continue to provide not only exciting research opportunities but also intriguing (and profitable) application niches in the future
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
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