Preface

**Section 3 High-Speed Optical Communication: Optical Systems 143**

Chapter 6 **Application of Complex Wavelet Packet Transform (CWPT) in**

Chapter 7 **Wired/Wireless Photonic Communication Systems Using**

Delgado, Ana Lilia Leal Cruz and Alicia Vera Marquina

Chapter 8 **New Results in DF Relaying Schemes Using Time Diversity for**

Alejandro García Juárez, Ignacio Enrique Zaldívar Huerta, Antonio Baylón Fuentes, María del Rocío Gómez Colín, Luis Arturo García

Rubén Boluda-Ruiz, Beatriz Castillo-Vázquez, Carmen Castillo-

**Coherent Optical OFDM (CO-OFDM) Communication Systems 145** Y. Ben-Ezra and B.I. Lembrikov

**Optical Heterodyning 169**

**VI** Contents

**Free-Space Optical Links 195**

Vázquez and Antonio García-Zambrana

#### **High-Speed Optical Communication**

High-speed optical communication is very much useful part in our advanced fibre-based telecommunication systems, data processing and networking systems. It consists of a trans‐ mitter that encodes the message signal into an optical signal, a channel/ link that carries this optical signal to its desired destination, and a receiver that reproduces the original message from the received optical signal. It presents up to date results of the communica‐ tion systems, along with the explanations of their relevance, from leading researchers in this field. The chapters of this book cover the general concepts of high-speed optical com‐ munication, devices used for optical communication, optical communication systems. In recent years, the optical components or devices and other enhanced signal processing func‐ tions are also considered in depth for high-speed optical communications systems. The researcher has also concentrated on optical devices such as light emitting diodes and pho‐ todetectors application in optical communication. This book is targeted at research, devel‐ opment and design engineers from the teams in manufacturing industry, academia and trlecommunication industries.

This book presents a high level technical overview of the emerging technologies of highspeed optical communication systems. It is intended as an introduction to the field for opti‐ cal communication and professional engineers, such as higher degree research students, research academics and design engineers. Although it is intended for professionals who al‐ ready have some technical background, it is nevertheless relevant to anyone wishing to un‐ derstand high-speed optical communication systems.

The following figure 1 illustrates a schematic diagram of a simple high-speed optical com‐ munication system. It consist of three separate parts or blocks, such as, (i) the transmitter part contains a constant optical/ light sources as laser or light emitting diodes (LEDs) and a modulator, (ii) the channel or link part is an optical fiber about 100-kms long that carries the information from the transmitter to the receiver, and (iii) the receiver consists of a semicon‐ ductor photodetector that detects the received signal and a semiconductor amplifier for the amplification of received signal from the channel/ link. The optical pulses are created using lasers or LEDs and transmitted through the transmitter via the links/ channels and receiving it at the receiver side. A list of bits (such as, '1's and '0's are as input data signal) are sent into the transmitter in the form of data/ signal levels (high '1' or low '0'), where they control a modulator, which alters the power of a light beam produced by a light sources such as lasers or LEDs. The laser or LED light sources produce 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 '1' or low '0' power levels. These optical pulses travel to a long distance, such as ~100-kms by total internal reflection inside the core of the fiber until they reach at the other end of the fiber, where they are focused onto a light detector (as a semiconductor pho‐ todetector that detects the received signals). In general, the following Fig. 1 covers all parts/ chapters concept of this book. These are: General concepts of high-speed optical communi‐ cation, Optical devices used in optical communication, and Optical communication systems.

**Figure 1.** A simple schematic diagram of a high-speed optical communication system/ link, where the transmitter con‐ tains a constant-power, optical/ light source as laser or LEDs and a modulator, the channel/ link is an optical fiber about 100-kms, and the receiver consists of a semiconductor photodetector and amplifiers.

#### **Organisation of the Book**

The authors with whom I have had the pleasure to collaborate have written chapters that report recent developments in high-speed optical communication and networking. They cover a number of themes, which include the basic concepts of optical communication, devi‐ ces used for high-speed optical communication, such as photodetectors and semiconductor amplifiers, optical communication systems 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: High-speed Optical Communication: Part 1, General Concepts; Optical Communication: Part 2, Optical Devices, such as Photodetectors and Light Emitting Diodes; Optical Commu‐ nication: and Part 3, Optical Communication Systems, such as Optical Transmission Sys‐ tems; Optical Communication. These categorisations of parts are not fully perfect because some of the chapters are mixed or overlapped 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 high-speed optical communication.

I acknowledge to all the authors for their contribution in the book chapters from different organisations (Universities and industries).

I acknowledge to Professor Zhu Quan Zang, Head of the Department of Electrical and Com‐ puter Engineering, Professor Michael Cloke, Dean of School of Engineering and Science, Curtin University Sarawak, Miri, Malaysia and Dr Yee Hong, Head of the Department of Electrical and Computer Engineering, Professor Syed Islam, Department of Electrical and Computer Engineering, Curtin University, Perth, Australia for their continuous support and encouragement to complete this task. I also acknowledge to Dr Mohammad Razaghi, Uni‐ versity of Kurdistan, Iran for his continuous support, encouragement and collaboration to complete this book.

I am very much grateful to Ms Danijela Duric, book publishing process manager/ Head at Intech, for her prompt responses to my queries in regards to complete this book. I wish all of my collaborators every success in their future research activities.

pulses of high '1' or low '0' power levels. These optical pulses travel to a long distance, such as ~100-kms by total internal reflection inside the core of the fiber until they reach at the other end of the fiber, where they are focused onto a light detector (as a semiconductor pho‐ todetector that detects the received signals). In general, the following Fig. 1 covers all parts/ chapters concept of this book. These are: General concepts of high-speed optical communi‐ cation, Optical devices used in optical communication, and Optical communication systems.

**Figure 1.** A simple schematic diagram of a high-speed optical communication system/ link, where the transmitter con‐ tains a constant-power, optical/ light source as laser or LEDs and a modulator, the channel/ link is an optical fiber

The authors with whom I have had the pleasure to collaborate have written chapters that report recent developments in high-speed optical communication and networking. They cover a number of themes, which include the basic concepts of optical communication, devi‐ ces used for high-speed optical communication, such as photodetectors and semiconductor amplifiers, optical communication systems 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

In this book, the chapters have been grouped as part according to the following themes: High-speed Optical Communication: Part 1, General Concepts; Optical Communication: Part 2, Optical Devices, such as Photodetectors and Light Emitting Diodes; Optical Commu‐ nication: and Part 3, Optical Communication Systems, such as Optical Transmission Sys‐ tems; Optical Communication. These categorisations of parts are not fully perfect because some of the chapters are mixed or overlapped 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

I acknowledge to all the authors for their contribution in the book chapters from different

I acknowledge to Professor Zhu Quan Zang, Head of the Department of Electrical and Com‐ puter Engineering, Professor Michael Cloke, Dean of School of Engineering and Science, Curtin University Sarawak, Miri, Malaysia and Dr Yee Hong, Head of the Department of Electrical and Computer Engineering, Professor Syed Islam, Department of Electrical and Computer Engineering, Curtin University, Perth, Australia for their continuous support and encouragement to complete this task. I also acknowledge to Dr Mohammad Razaghi, Uni‐ versity of Kurdistan, Iran for his continuous support, encouragement and collaboration to

about 100-kms, and the receiver consists of a semiconductor photodetector and amplifiers.

the indicators of scientific progress in high-speed optical communication.

**Organisation of the Book**

VIII Preface

that we have been able to include in this book.

organisations (Universities and industries).

complete this book.

Foremost' I would like to thank my wife Mrs Varoti Das, son Nishikanta Das and daughter Nandita Das for their strong patience' understanding, continuous encouragement and sup‐ port to complete this book.

#### **Narottam Das**

Department of Electrical and Computer Engineering Curtin University Sarawak, Miri, Malaysia

Department of Electrical and Computer Engineering Curtin University, Perth, Australia

**High-Speed Optical Communication: General Concepts**
