1,720,981 research outputs found
Coupling ratio tuning of direct UV-written X-couplers for cascaded power splitters in WDM networks
Full text linkWe present a study of low polarisation sensitivity 2 degrees X-couplers with 20% coupling ratio tuning via refractive index asymmetry, attaining 50:50 power splitting at 1550nm. The device has less than 5% coupling ratio variation over 30nm in the C-band and <0.7dB polarisation dependent loss
In vacuo measurement of the sensitivity limit of planar Bragg sensors
No full textWe present the direct measurement and modeling of the sensitivity limit of an integrated refractive index sensor for the detection of molecular monolayers. Direct UV writing can be used to fabricate a wide range of integrated optical devices particularly Bragg gratings. These Bragg gratings are inherently sensitive to temperature and strain
Compact coupler designs for quantum optical circuits produced by direct UV writing
Full text linkIntegrated planar lightwave circuits (PLCs) provide a promising route to small-scale quantum optical networks [1]. Recent work on quantum logic gates using silica-based PLCs has highlighted the opportunities afforded by the ability to coherently manipulate degrees of freedom at the level of single photons [2]. Increasingly complex waveguide networks are required for linear optics quantum computing (LOQC), a route towards small scale quantum information processing [3]. This approach uses quantum interference between photons and measurements with feedforward to implement the nonlinear interactions between photons that are required for information processing. A major issue in developing such circuits is the internal loss and the coupling efficiency of input photon from optical fibers
Monitoring the deflection of a membrane using direct UV written planar Bragg gratings
No full textA thin (~100 µm thick) silica-on-silicon square membrane (10 mm x 10 mm) has been fabricated and its deflection monitored through a 100 Bragg grating array defined within the membrane
In situ loss measurement of direct UV written waveguides using integrated Bragg gratings
No full textThe propagation loss of a direct UV-written silica-on-silicon waveguide is measured using an elegant nondestructive method. The technique uses integrated Bragg grating structures, which are observed from opposing launch directions to obtain information about the optical power at different positions along the length of the waveguide. Critically, the technique is ratiometric and independent of coupling loss and grating variability. This high-precision measurement is suitable for low-loss planar waveguides. From this data, the propagation loss of the UV-written waveguides was observed to be 0.235±0.006dB/cm.<br/
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
16-µJ pulse energy, picosecond, narrow-linewidth master oscillator power amplifier using direct amplification
No full textWe present a gain-switched-diode-seeded 1034.5nm master oscillator power amplifier, employing direct amplification through standard commercial Yb3+-doped fibres to generate 15.6µJ-pulse-energy, 126kW-peak-power, picosecond pulses with 3dB spectral bandwidth of 0.87nm
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