1,721,049 research outputs found
Recent progress in waveguide-integrated graphene photonic devices for sensing and communication applications
No full textGraphene is a two-dimensional material with numerous intriguing optical properties, such that graphene photonic devices have attracted great interest for sensing and communication applications. However, surface-illuminated graphene photonic devices usually suffer from weak light-matter interactions due to the atomic-layer thickness of graphene, seriously limiting the performances of such devices. To tackle this problem, waveguide-integrated graphene photonic devices have been demonstrated since 2010, which offer the advantage of much longer interaction length between the evanescent field of the optical waveguide and graphene than the surface-illuminated devices. Moreover, the fabrication of waveguide-integrated graphene photonic devices is compatible with CMOS technology, allowing potentially low-cost and high-density on-chip integration. To date, a tremendous interest is growing in the hybrid integration platform composed of graphene and silicon photonic integrated circuits. In this paper, we review the recent progress in waveguide-integrated graphene photonic devices and their applications in sensing and communication.</p
Blazed subwavelength grating coupler
No full textShort-wavelength mid-infrared (2–2.5 μm wave band) silicon photonics has been a growing area to boost the applications of integrated optoelectronics in free-space optical communications, laser ranging, and biochemical sensing. In this spectral region, multi-project wafer foundry services developed for the telecommunication band are easily adaptable with the low intrinsic optical absorption from silicon and silicon dioxide materials. However, light coupling techniques at 2–2.5 μm wavelengths, namely, grating couplers, still suffer from low efficiencies, mainly due to the moderated directionality and poor diffraction-field tailoring capability. Here, we demonstrate a foundry-processed blazed subwavelength coupler for high-efficiency, wide-bandwidth, and large-tolerance light coupling. We subtly design multi-step-etched hybrid subwavelength grating structures to significantly improve directionality, as well as an apodized structure to tailor the coupling strength for improving the optical mode overlap and backreflection. Experimental results show that the grating coupler has a recorded coupling efficiency of −4.53 dB at a wavelength of 2336 nm with a 3-dB bandwidth of ∼107 nm. The study opens an avenue to developing state-of-the-art light coupling techniques for short-wavelength mid-infrared silicon photonics
Integrated optical spectrometers on silicon photonics platforms
No full textSpectroscopy plays a pivotal role in discerning the chemical and biochemical compositions of analytes, significantly impacting chemical and material analysis, disease diagnosis, environmental monitoring, and space exploration. Despite the widespread demand for optical spectrometers in both industry and academia, their deployment in many practical applications is hindered by the high costs, large footprints, and mechanical vibration sensitivity of conventional spectrometers. These problems are addressed by integrated optical spectrometers. Silicon photonics offers a potentially low-cost platform for ultracompact integrated optical spectrometers, leveraging the complementary metal-oxide-semiconductor (CMOS) compatible fabrication technology and high flexibility in on-chip light manipulation of high-index waveguides. The integrated optical spectrometers on silicon photonics platforms provide promising solutions for developing ultra-compact and cost-effective spectral analyzers in various applications. This review paper overviews recent advancements in integrated optical spectrometers on silicon photonics platforms over the past decades, focusing on their fundamental principles, design methodologies, spectral performances, and potential applications. By blending foundational knowledge with cutting-edge research, this review aims to involve researchers from different fields, including spectroscopy, materials science, astronomy, environmental engineering, and beyond.</p
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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