1,720,964 research outputs found
Dataset underpinning "Quasi-Phase-Matched Materials for Active Sensing in the Mid-Infrared Waveband"
No full textData collected as part of the Southampton University Doctoral Thesis "Quasi-Phase-Matched Materials for Active Sensing in the Mid Infrared Waveband". Includes metrology and transmission data of various methods of machining and bonding GaAs and BK7 structures. Additionally spectral information relating to nonlinear generation in a PPLN OPO, RTA OPA and InF3 fibre. This dataset represents raw measured data used to generate many of the graphs and figures in the thesis.</span
Evaluation of thick silicon nitride film properties at 300 mm scale for high-Q photonic devices
No full textThis work evaluates thick silicon nitride (SiN) film properties using various inline and offline advanced metrology data analysis. The thick SiN films for photonic applications are typically prepared by plasma-enhanced chemical vapor deposition (PECVD) and low-pressure chemical vapor deposition (LPCVD) techniques. Our present study combines high-volume inline and high-accuracy offline metrology to best characterize our thick SiN films. The developed SiN film compositional analysis has been carried out using inline X-ray photoelectron spectroscopy (XPS) to get fast feedback on the composition and contamination of the film surface. Finally, we present a refractive index (n) comparison for annealed and unannealed PECVD/LPCVD wafers
Photonic microcantilevers with interferometric Bragg grating interrogation
No full textGermanosilicate glass microcantilevers are fabricated featuring an integrated Fabry-Pérot interferometer. Direct UV writing of single-mode planar waveguides and Bragg gratings is combined with physical micromachining, using a precision dicing saw, to realize glass microcantilevers on a silicon platform. The device presented here has a wavelength shift force sensitivity of 330 nm/N, which is calibrated using a surface profilometer measurement and is an order of magnitude better than current state-of-the-art Bragg-grating-based sensors. The device also shows an approximately tenfold increase in amplitude modulation compared with a similar device architecture utilizing a single Gaussian-apodized Bragg grating. By forming the Fabry-Pérot cavity around the point of greatest strain, we reduce the unwanted effects of grating chirp as the cantilever is deflected and relate the performance to a mechanical model that relates cavity phase shift to deflection
Upconversion detection of 1.25 Gb/s Mid-IR telecommunications using a silicon avalanche photodiode
No full textWe present our current work investigating telecommunication transmission in the mid-infrared region and detection in the silicon absorption band. We achieve 10-7 bit error rates using commercial lasers in single-pass nonlinear conversion stages using MgO:PPLN
Advanced metrology of thick silicon nitride films at 300 mm scale for next generation high-Q photonic devices
No full textThe proposed paper will present various inline and offline advanced metrology data of thick SiN films (~>500 nm) prepared by plasma-enhanced chemical vapor deposition (PECVD) and low-pressure chemical vapor deposition (LPCVD) techniques. Our study combines high-volume inline and high-accuracy offline metrology to best characterize our thick SiN films. We present a refractive index (n) comparison for annealed and unannealed PECVD/LPCVD wafers
Integrated optic glass microcantilevers with Bragg grating interrogation
No full textA new method for creating microcantilevers in glass allows integration of optical waveguides and Bragg gratings. Devices are fabricated by high precision sawing, followed by direct UV writing of waveguides with Bragg gratings and then chemical etching to release the freestanding glass structures. Optical measurement of the Bragg gratings together with piezo-actuation allows the mechanical resonances to be probed. By measuring the mechanical damping coefficient of the cantilever as a function of the gas pressure in a vacuum system the transition from the viscous to the molecular flow regime can be observed
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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