1,721,054 research outputs found
Multidiameter optical ring and Hermite–Gaussian vortices for wavelength division multiplexing–mode division multiplexing
Full text linkOptical vortices are high-capacity data carriers for mode division multiplexing (MDM) in multimode fiber (MMF). This paper reports on the MDM of a combination of helical-phased optical vortices comprising donut modes and Hermite–Gaussian (HG) modes for different radial offsets from the MMF axis. A data rate of 44 Gbps is achieved for wavelength division multiplexing–MDM of two pairs of helical-phased donut mode and HG mode at wavelengths 1550.12 and 1551.72 nm for a MMF length of 1500 m
5 × 5 25 Gbit/s WDM-MDM
Full text linkWavelength-division multiplexed-passive optical network (WDM-PON) is a revolutionary high-capacity and scalable broadband access network. This paper capitalizes on Laguerre–Gaussian (LG) modes to reduce modal dispersion and increase data capacity. A data rate of 25 Gbit/s is attained for a multimode fiber link by multiplexing five LG modes on five wavelengths centered at 1,550.12 nm for a distance up to 800 m
The role and challenges of free-space optical systems
No full textComplementing wireless radio networks with free-space optics (FSO) achieves high data rates by modulating radio subcarriers over an optical carrier without expensive optical fiber cabling, enabling a pervasive platform for reaching underserved areas.In this paper, we review the main features of FSO for terrestrial and inter-satellite communications. Simulations of 1 Gbps data transmission through FSO links in both terrestrial and inter-satellite communications have been investigated to highlight potential atmospheric challenges in FS
Design of Excess 3 to BCD code converter using electro-optic effect of Mach-Zehnder Interferometers for efficient data transmission
Full text linkExcess 3 code is one of the most important codes used for efficient data storage and transmission. It is a non-weighted code and also known as self complimenting code. In this paper, a four bit optical Excess 3 to BCD code converter is proposed using electro-optic effect inside lithium-niobate based Mach-Zehnder interferometers (MZIs). The MZI structures have powerful capability to switching an optical input signal to a desired output port. The paper constitutes a mathematical description of the proposed device and thereafter simulation using MATLAB. The study is verified using beam propagation method (BPM).Dehradun Institute of Technology (Dehradun, India). Faculty Research Scheme (Ref. No.: DITU/R&D/2014/7/ECE
An optical synchronous up counter based on electro-optic effect of lithium niobate based Mach–Zehnder interferometers
Full text linkSequential circuits have the ability to store, retain and then retrieve information when needed at a later time. They act as storage elements and have memory. However, due to ever increasing demand of data rate, already existing electronic signal processing devices have become obsolete due to their large latency. To overcome the existing bottleneck, a 4-bit synchronous up counter using electro-optic effect of Mach–Zehnder interferometer has been proposed. The study is carried out by simulating the proposed device with beam propagation method
Implementation of 2-bit multiplier based on electro-optic effect in Mach–Zehnder interferometers
Full text linkThis paper demonstrates the structure and working principle of an optical 2-bit multiplier using lithium niobate (LiNbO[subscript 3]) based Mach–Zehnder interferometer (MZI). The powerful ability of MZI structures to switch the optical signal from one output port to the other output port has been used in the implementation of the proposed 2-bit multiplier. The paper constitutes the mathematical description of the 2-bit multiplier and thereafter compilation using MATLAB. The study is carried out by simulating the proposed device with Beam propagation method (BPM).DIT University (Faculty Research Scheme Ref. No.: DITU/R&D/2014/7/ECE
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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