Xem 1-20 trên 296 kết quả Optical communications
  • When a fiber-optic link is neither practical nor feasible, under the above scenario, wireless optical communications (WOC) becomes a real alternative, since it allows to transfer data with high-bandwidth requirements with the additional advantages of wireless systems (Arimoto, 2010; Ciaramella et al., 2009; Sova et al., 2006). Moreover, a wireless optical communication system offers, when compared with RF technology, an intrinsic narrower beam; less power, mass and volume requirements, and the advantage of no regulatory policies for using optical frequencies and bandwidth....

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  • Since the publication of the first edition of this book in 1992, the state of the art of fiber-optic communication systems has advanced dramatically despite the relatively short period of only 10 years between the first and third editions. For example, the highest capacity of commercial fiber-optic links available in 1992 was only 2.5 Gb/s. A mere 4 years later, the wavelength-division-multiplexed (WDM) systems with the total capacity of 40 Gb/s became available commercially.

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  • Most of the material in this volume is new. The first three chapters deal with three important fiber-optic components--fiber-based gratings, couplers, and interferometers--that serve as the building blocks of lightwave technology. In view of the enormous impact of rare-earth-doped fibers, amplifiers and lasers made by using such fibers are covered in Chapters 4 and 5. The last three chapters describe important applications of nonlinear fiber optics and are devoted to pulse-compression techniques, fiber-optic communication systems, and soliton-based transmission schemes....

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  • (BQ) The book is divided into 2 parts, part 1 from chapter 21 to chapter 38. This part includes the contents: Mobile ad hoc network routing, security for ad hoc networks, phishing attacks and countermeasures, chaos-based secure optical communications using semiconductor lasers, chaos applications in optical communications,...and other contents.

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  • ©2005 Springer Science + Business Media, Inc. Print ©2005 Springer Science + Business Media, Inc. Boston All rights reserved No part of this eBook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher Created in the United States of America

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  • Optical Amplifiers As seen in Chapter 5, the transmission distance of any fiber-optic communication system is eventually limited by fiber losses. For long-haul systems, the loss limitation has traditionally been overcome using optoelectronic repeaters in which the optical signal is first converted into an electric current and then regenerated using a transmitter. Such regenerators become quite complex and expensive for wavelength-division multiplexed (WDM) lightwave systems.

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  • Optical Transmitters The role of the optical transmitter is to convert an electrical input signal into the corresponding optical signal and then launch it into the optical fiber serving as a communication channel. The major component of optical transmitters is an optical source. Fiber-optic communication systems often use semiconductor optical sources such as light-emitting diodes (LEDs) and semiconductor lasers because of several inherent advantages offered by them.

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  • A communication system transmits information from one place to another, whether separated by a few kilometers or by transoceanic distances. Information is often carried by an electromagnetic carrier wave whose frequency can vary from a few megahertz to several hundred terahertz. Optical communication systems use high carrier frequencies (∼ 100 THz) in the visible or near-infrared region of the electromagnetic spectrum.

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  • Optical communication is very much useful in telecommunication systems, data processing and networking. It consists of a transmitter that encodes a message into an optical signal, a channel that carries the signal to its desired destination, and a receiver that reproduces the message from the received optical signal. It presents up to date results on communication systems, along with the explanations of their relevance, from leading researchers in this field.

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  • Lightwave Systems The preceding three chapters focused on the three main components of a fiber-optic communication system—optical fibers, optical transmitters, and optical receivers. In this chapter we consider the issues related to system design and performance when the three components are put together to form a practical lightwave system. Section 5.1 provides an overview of various system architectures. The design guidelines for fiberoptic communication systems are discussed in Section 5.2 by considering the effects of fiber losses and group-velocity dispersion.

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  • Dispersion Management It should be clear from Chapter 6 that with the advent of optical amplifiers, fiber losses are no longer a major limiting factor for optical communication systems. Indeed, modern lightwave systems are often limited by the dispersive and nonlinear effects rather than fiber losses. In some sense, optical amplifiers solve the loss problem but, at the same time, worsen the dispersion problem since, in contrast with electronic regenerators, an optical amplifier does not restore the amplified signal to its original state.

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  • Soliton Systems The word soliton was coined in 1965 to describe the particle-like properties of pulses propagating in a nonlinear medium [1]. The pulse envelope for solitons not only propagates undistorted but also survives collisions just as particles do. The existence of solitons in optical fibers and their use for optical communications were suggested in 1973 [2], and by 1980 solitons had been observed experimentally [3].

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  • Multichannel Systems In principle, the capacity of optical communication systems can exceed 10 Tb/s because of a large frequency associated with the optical carrier. In practice, however, the bit rate was limited to 10 Gb/s or less until 1995 because of the limitations imposed by the dispersive and nonlinear effects and by the speed of electronic components. Since then, transmission of multiple optical channels over the same fiber has provided a simple way for extending the system capacity to beyond 1 Tb/s.

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  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Reed-Solomon Turbo Product Codes for Optical Communications: From Code Optimization to Decoder Design

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  • Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Differential Amplitude Pulse-Position Modulation for Indoor Wireless Optical Communications

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  • ISBN: 0-8247-0777-X This book is printed on acid-free paper. Headquarters Marcel Dekker, Inc. 270 Madison Avenue, New York, NY 10016 tel: 212-696-9000; fax: 212-685-4540 Eastern Hemisphere Distribution Marcel Dekker AG Hutgasse 4, Postfach 812, CH-4001 Basel, Switzerland tel: 41-61-261-8482; fax: 41-61-261-8896 World Wide Web http://www.dekker.com The publisher offers discounts on this book when ordered in bulk quantities. For more information, write to Special Sales=Professional Marketing at the headquarters address above. Copyright # 2002 by Marcel Dekker, Inc. All Rights Reserved.

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  • Digital communications is a rapidly advancing applications area. Significant current activities are in the development of mobile communications equipment for personal use, in the expansion of the available bandwidth (and hence information carrying capacity) of the backbone transmission structure through developments in optical fibre, and in the ubiquitous use of networks for data communications.

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  • In this book, the chapters have been grouped as part according to the following themes: Optical Communications Systems: Part 1, General Concepts; Optical Communications Systems: Part 2, Amplifiers and Networks; Optical Communications Systems: Part 3, Optical Multiplexing and Demultiplexing; Optical Communications Systems: Part 4, Network Traffic. These categorisations of parts are not fully perfect because some of the chapters are mixed i.e., like an inter- disciplinary topic.

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  • We have witnessed significant advances in multimedia research and applications due to the rapid increase in digital media, computing power, communication speed, and storage capacity. Multimedia has become an indispensable aspect in contemporary daily life, and we can feel its presence in many applications ranging from online multimedia search, Internet Protocol Television (IPTV), and mobile multimedia, to social media.

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  • Although inelastic scattering of light from molecules, a phenomenon now known as Raman scattering, was observed by C. V. Raman in 1928, the nonlinear phenomenon of stimulated Raman scattering was not demonstrated until 1962. Soon after low-loss silica fibers became available around 1970, Roger Stolen and coworkers used stimulated Raman scattering in such fibers not only for amplification of optical signals but also for constructing fiber-based Raman lasers.

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