1,720,978 research outputs found
Experimental confirmation of Matched Bends
No full textModal conversion between the fundamental mode and the first-order (leaky) mode has been experimentally investigated in high-index-contrast integrated-optical bent waveguides. The matched bend condition has been experimentally confirmed on cascaded bends, and the effect of both matched and unmatched bends on Y branches has been investigated. Good agreement between theoretical predictions and experimental results for both monomode and multimode waveguides is achieved. It is demonstrated that, in bent waveguides, the modal conversion between the fundamental mode and the first (leaky) mode can be accurately controlled to avoid additional losses and transfer function impairments
Experimental Bit Error rate penalty evaluation of ring resonators filters on non return to zero transmission systems
No full textThe paper discusses an experimental investigation of the impact of a single ring resonator and a double ring resonator filter on the performance of an optical communication Non Return to Zero system at 2.5 and 10 Gbit/s. Bit Error Rate curves are reported and discussed. Experiments demonstrate that filtering and routing channels of dense wavelength division multiplexed systems is possible and advantageous with ring resonator filters
A 0.18um CMOS Selective Receiver Front-end for UWB applications
No full textThis paper addresses the problem of 5–6-GHz WLAN
interferer rejection in a direct-conversion receiver front-end for
multi-band orthogonal frequency division multiplexing (OFDM)
ultra-wideband (UWB) applications. The IC, realized in a 0.18- um
CMOS technology, comprises a single-ended voltage–voltage feedback
low-noise amplifier (LNA) and a quadrature mixer. The
LNA employs a double-peak single-notch network in the output
load, amplifying UWB groups #1 and #3, while rejecting WLAN
interferes in the 5–6-GHz frequency range. The mixer, based on a
merged quadrature topology, also realizes a second-order low-pass
filtering.
Fabricated dies have been bonded on PCB for characterization.
The front-end, drawing 10 mA from 1.8 V, achieves a 1-dB gain
desensitization with a 6.5-dBm interferer power at 5.5 GHz.
Other measured performances are 5.2-dB and 7.7-dB minimum
and maximum noise figure (NF), 3.5-dBm minimum IIP3 and
+34.5-dBm minimum in-band IIP2 and +21-dBm out-of-band
IIP2
A Magnetically Tuned Quadrature Oscillator
No full textContinuous frequency tuning by control of the magnetic field of a transformer—capacitor tank, in a selective oscillator, is explored in this work. A quadrature generator is built connecting two identical transformer—capacitor oscillator cells in a feedback loop. The topology itself assures the currents in the transformer windings are aligned in phase, while their relative amplitude determines, via magnetic coupling, oscillators’ tank reactance,i.e., oscillation frequency. This paper introduces the idea, analyzesoscillation amplitude, frequency tuning band, phase noise, and phase accuracy, and discusses design and experiments. Prototypes,realized in 65 nm CMOS, employing MOS varactors to further extend operation bandwidth, show the following performances:3.2 GHz and 7.3 GHz minimum and maximum oscillation orequency, respectively. Phase noise figure of merit of 176.5 dBat 3.2 GHz and 170.5 dB at 6.4 GHz is observed, with 24 mWmaximum power consumption and 1.5 maximum deviation fromquadrature
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
High-contrast waveguides in sputtered pure TeO2 glass thin films
No full textWe present a technological approach to the realization of
channeled optical waveguides, starting from reactively sputtered tellurite
glass thin films, grown on silica-coated 4” Si wafers. In particular, optical
lithographic process and etching recipes have been developed to overcome
the solubility of TeO2 films in aqueous solutions, and to process them into
high-index contrast structures with minimized post-etch roughness. Optical
tests on preliminary rib waveguide geometries feature 6.3 dB/cm
propagation loss for fundamental TE mode at λ = 1.5 μm
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