1,721,026 research outputs found
Stable 100 GHz Pulses Generated by injection locking of multiple lasers to an optical frequency comb
No full textOptical frequency combs (OFCs) can generate a wide bandwidth of regularly spaced modes with high frequency stability. Besides frequency and time metrology, OFCs can also have applications in arbitrary waveform generation and telecommunications by manipulating individual comb modes. We have previously demonstrated using optical injection locking to selectively amplify individual comb modes which are closely spaced (250 MHz) [1]. Over 50 dB of gain was achieved with low phase noise associated with the locking process [2]. The injection locking process maintains the coherence properties of the master laser and therefore by combining multiple lasers locked to different frequencies of a common OFC, pulses can be generated
Selective amplification of frequency comb modes via optical injection locking of a semiconductor laser: influence of adjacent unlocked comb modes
No full textOptical injection locking can be used to isolate and amplify individual comb modes from an optical frequency comb (OFC). However, it has been observed that for narrow spaced OFCs (e.g. 250 MHz), the adjacent comb modes are still present in the output of the locked laser. These residual modes experience some amplification relative to the injected signal, however the gain is significantly less than for the locked mode. We report the measurement of this sidemode amplification for a semiconductor laser injection locked to a 250 MHz spaced OFC. It was found that this amplification can be well suppressed by tuning the frequency difference between the free running laser and the OFC mode it was locked to. The sidemode amplification was then investigated numerically by solving the laser rate equations under optical injection. It was found that the main contribution to the sidemode amplification was due to phase modulation induced by the residual comb modes. The detuning dependent suppression occurs due to destructive interference between pairs of equidistant comb modes
Wavelength conversion by injection locking to an optical comb for optical frequency transfer applications
No full textThe transfer of ultra-stable optical frequencies through existing telecommunication fibre links is required to enable comparison of the most advanced optical clocks which are generally housed in National Metrology Institutes and typically separated by distances of a few 100 km to 1500 km. To meet the need for transparency in optical communication networks it is necessary to be able to shift the carrier wavelength between ITU-T channels in the C-band (1530 - 1565 nm). Here, we propose use of optical injection locking of a semiconductor laser to an optical comb to enable wavelength conversion in precision optical frequency transfer applications. The optical comb source used (from OptoComb Inc.) comprises a LiNbO3 phase modulator (PM) within a resonant cavity and generates a comb which spans the full C-band with a line spacing of 25 GHz
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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