1,720,958 research outputs found
Erbium-doped fibre amplifier in a 16-channel coherent broadcast network
No full textIn this paper, we describe the use of an erbium-doped fibre amplifier in a 16-channel coherent broadcast network experiment operating in the wavelength range of 1538.8 to 1540nm. The fibre-to-fibre gain was 22dB and the amplifier dynamic range was 15dB for the entire transmission spectrum. The amplifier was used to amplify sixteen 155Mb/s signals on one output of a 16-by-16 star coupler, allowing a total span loss of 47dB between transmitted and received signals. Satisfactory transmission system performance is obtained for error ratios of 10-9
The effect of four-wave mixing in fibers on optical frequency-division multiplexed systems
No full textThe optical nonlinearity in a single-mode fiber imposes a fundamental limitation on the capacity of optical frequency-division multiplexed (OFDM) systems. In particular, four-wave mixing (FWM) crosstalk may severely degrade the system performance when the fiber input powers are large and/or the channel spacing is too small. Theoretical and experimental results of the effects of FWM in OFDM systems are presented The theoretical results demonstrate the dependence of FWM on various systems parameters. Also included is an analysis of FWM in both unidirectional and bidirectional transmission systems. The receiver sensitivity degradation from FWM crosstalk was measured in a 16-channel coherent system. A sensitivity penalty of 0.4 dB resulted when a signal power of -3 dBm/channel was transmitted through 12 km of dispersion-shifted fiber
Performance of an erbium-doped fiber amplifier in a 16-channel coherent broadcast network experiment
No full textAn erbium-doped fibre amplifier was used in a 16-channel coherent broadcast network experiment operating in the wavelength range of 1538.8 to 1540.0 nm. The fibre-to-fibre gain was 22dB and the amplifier dynamic range was 15dB for the entire transmission spectrum. This enabled the distribution of sixteen 155Mb/s signals to one of 256 end-users at a distance of 102 km
Fibre four-wave mixing induced by optical amplification in a 16 channel coherent system
No full textIn optical frequency division multiplexed systems, the nonlinear interaction between signal channels may set the ultimate limit on the allowable channel spacing, total number of channels, and maximum power per channel. The four-wave mixing (FWM) crosstalk in semiconductor amplifiers has been shown to cause a sensitivity degradation when the channel spacing is a few hundred megahertz. In contrast, when fiber amplifiers are used, nonlinear interactions have been considered negligible because of the long fluorescence time constant. However, we recently found that for a fiber amplifier with a saturation power in the 5-10-mW range, the transmission fiber following the amplifier can cause FWM crosstalk. Fiber FWM may also be observed without an amplifier if a wavelength selective coupler is used to combine the laser outputs with no splitting loss
Fibre four-wave mixing in multi-channel coherent systems
No full textThe crosstalk degradation due to four-wave mixing (FWM) in fiber is studied in a 155Mb/s, 16 channel coherent system with the signal powers amplified by an erbium-doped fiber amplifier. When a total power of +8.4dBm (0.46mW/channel) is launched into the fiber, the crosstalk degradation is 0.4dB. A theoretical study indicates the EWM dependence on fiber chromatic dispersion, the total number of channels, and the signal power levels and polarization states
Performance of erbium-doped fibre amplifier in 16-channel coherent broadcast network
No full textThe performance of an erbium doped fibre amplifier in a 16-channel coherent broadcast network operating at 155 Mbit/s has been experimentally investigated. A fibre-to-fibre gain of 22dB at 1540nm allowed simulation of a network that serves 256 end-users over a distance of 102 km
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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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