1,720,973 research outputs found
2.8µm emission of Er-doped CaF<sub>2</sub> planar waveguides fabricated by molecular beam epitaxy
No full textWe report the fabrication of erbium doped calcium fluoride thin film optical waveguides by molecular beam epitaxy and the luminescence study of the 2.8µm emission from a guide with an erbium concentration of 13 at. % under pumping at 980nm
Laser operation of a Nd:LaF<sub>3</sub> thin film grown by molecular-beam epitaxy
No full textWe present the first laser operation of a dielectric waveguide fabricated by molecular-beam epitaxy. Details of the growth process, the Nd:LaF3 spectroscopic properties, and the laser performance at 1.06µm are given
Nd:LaF<sub>3</sub> channel waveguide lasers fabricated by molecular beam epitaxy
No full textWe report the first laser operation of slab-loaded channel waveguides based on Nd:LaF3 thin films grown by molecular beam epitaxy. Two different methods of channel fabrication in this low phonon energy material are discussed
Nd:LaF<sub>3</sub> waveguide laser fabricated by molecular beam epitaxy
No full textWe describe the first demonstration of laser action in a dielectric waveguide grown by molecular beam epitaxy. Laser emission at 1.063µm is obtained from a Nd:LaF3 thin film grown on a CaF2 substrate
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
Gain measurements at 2.8µm and fluorescence spectroscopy in Er:LaF<sub>3</sub> waveguides fabricated by molecular beam epitaxy
No full textThe potential of MBE rare-earth-doped LaF3 thin films in the IR region has been previously reported by our group. Despite an unfavourable electron-phonon coupling which does not permit access to efficient transitions far above 3µm, LaF3 still offers the advantage of a very low phonon energy (~380 cm-1) and high transparency in the 2µm - 3µm range. Therefore it appears very attractive to fabricate a 2.8µm laser device based on this technology, with erbium as the doping ion, as the waveguide geometry should lead to a low-threshold, efficient, integrated device that operates continuously at room-temperature.Several erbium-doped LaF3 thin films were grown on (111) oriented CaF2 substrates with core depths in the 2µm range, both with or without CaF2 claddings. The design with a cladding gives a high NA of 0.7 and offers single mode properties and good vertical confinement at 2.8µm as shown in figure 1. Three samples of 19 mm length, with respective concentrations of 1.08, 5.1 and 8.9 at. %, were grown by this method for investigation
Elaboration et caractérisations optiques de guides plans de LaF<sub>3</sub> doped Nd<sup>3+</sup>
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