Optical Communications Systems

274 Pages·2012·13.136 MB·English

by  N. Das

OPTICAL
COMMUNICATIONS
SYSTEMS

Edited by Narottam Das
Optical Communications Systems
Edited by Narottam Das

Published by InTech
Janeza Trdine 9, 51000 Rijeka, Croatia

Copyright © 2012 InTech
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First published February, 2012
Printed in Croatia

A free online edition of this book is available at www.intechopen.com
Additional hard copies can be obtained from [email protected]

Optical Communications Systems, Edited by Narottam Das
p. cm.
978-953-51-0170-3

Contents

Preface IX
Part 1 Optical Communications Systems:
General Concepts 1
Chapter 1 Wireless Optical Communications
Through the Turbulent Atmosphere: A Review 3
Ricardo Barrios and Federico Dios
Chapter 2 Effect of Clear Atmospheric Turbulence on Quality of
Free Space Optical Communications in Western Asia 41
Abdulsalam Alkholidi and Khalil Altowij
Chapter 3 Full-Field Detection with Electronic Signal Processing 75
Jian Zhao and Andrew D. Ellis
Part 2 Optical Communications Systems:
Amplifiers and Networks 101
Chapter 4 Hybrid Fiber Amplifier 103
Inderpreet Kaur and Neena Gupta
Chapter 5 Physical-Layer Attacks in
Transparent Optical Networks 123
Marija Furdek and Nina Skorin-Kapov
Chapter 6 The Least Stand-By Power System
Using a 1x7 All-Optical Switch 147
Takashi Hiraga and Ichiro Ueno
Part 3 Optical Communications Systems:
Multiplexing and Demultiplexing 163
Chapter 7 Optical Demultiplexing Based on Four-Wave
Mixing in Semiconductor Optical Amplifiers 165
Narottam Das and Hitoshi Kawaguchi
VI Contents

Chapter 8 Realization of HDWDM Transmission System
with the Minimum Allowable Channel Interval 191
Jurgis Porins, Vjaceslavs Bobrovs and Girts Ivanovs
Chapter 9 Design and Modeling of
WDM Integrated Devices Based on Photonic Crystals 211
Kiazand Fasihi
Part 4 Optical Communications Systems: Network Traffic 245
Chapter 10 Traffic Engineering 247
Mahesh Kumar Porwal

Preface

Optical Communications Systems
Optical Communications Systems are very much essential part in our advanced
fibre-based telecommunications and networks. They consists of a transmitter that
encodes a message into an optical signal, a channel that carries the signal to its
destination, and a receiver that reproduces the message from the received optical
signal. This book presents up to date results on communication systems, along with
the explanations of their relevance, from leading researchers in this field. Its
chapters cover general concepts of optical and wireless optical communication
systems, optical amplifiers and networks, optical multiplexing and demultiplexing
for optical communication systems, and network traffic engineering. Recently,
wavelength conversion and other enhanced signal processing functions are also
considered in depth for optical communications systems. The researcher has also
concentrated on wavelength conversion, switching, demultiplexing in the time
domain and other enhanced functions for optical communications systems. This
book is targeted at research, development and design engineers from the teams in
manufacturing industry; academia and telecommunications service operators/
providers.
This book presents a high level technical overview of the emerging technologies of
optical communications and networking systems. It is intended as an introduction to
the field for optical communication systems or network professionals, such as higher
degree research students, academics and design engineers. Although it is intended for
professionals who already have some technical background, it is nevertheless relevant
to anyone wishing to understand optical communication systems or networks.
Figure 1 illustrates a simple schematic diagram of an optical communication system. It
consist of three separate parts, namely, the transmitter contains a constant-power light
source as laser and a modulator, the channel is an optical fiber about 100-kms that
carries the information from transmitter to receiver, and the receiver consists of a
semiconductor photodetector that detects the received signal and an optical amplifier
for the amplification of received signal. Optical pulses are created using lasers/
amplifiers and transmitted through the transmitter via channels and receiving at the
receiver. A list of bits (‘1’s and ‘0’s as an input signal) are sent into the transmitter in
X Preface

the form of signal levels (high or low), where they control a modulator, which alters
the power of a light beam produced by a light source (laser or amplifier). The light
source (laser or amplifiers) produces a constant-power light beam, which experiences
different amount of attenuation as it passes through the modulator, depending on the
bit value is being sent. The light emerging from the modulator is a series of optical
pulses of high or low power levels. These optical pulses travel as far as ~100-kms by
total internal reflection inside the core of the fiber until they reach at the other end,
where they are focused onto a light detector (as a semiconductor photodetector that
detects the received signals). In general, Fig. 1 covers all parts/ chapters’ concept of this
book. These are: General Concepts, Amplifiers and Networks, Optical Multiplexing
and Demultiplexing and Network Traffic.
010010101010
Input Signal bits
Optical Pulses Output Signal bits
010010101010
Light Source
Laser Modulator Photo- Optical
detector Amplifier
Optical Fiber
(~ 100 kms)
Transmitter Channel Receiver

Fig. 1. A simple schematic diagram of an optical communication system, where the
transmitter contains a constant-power light source as laser and a modulator, the
channel is an optical fiber about 100-kms, and the receiver consists of a semiconductor
photodetector and an optical amplifier.
Organisation of the Book
The authors with whom I have had the pleasure to collaborate have written chapters
that report recent developments in optical communications systems. They cover a
number of themes, which include the basic optical communications systems,
multiplexing and demultiplexing, traffic engineering, amplifiers and optical networks
design as described above. No book of the current length can encompass the full scope
of the subject but I am pleased at the range of topics that we have been able to include
in this book.
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. However, all of the chapter are within an easily identifiable
subject boundary that is a positive sign of the indicators of scientific progress in
optical communications systems.