Optic Fibre Communication

ABSTRACT

The growth of the fiber optics industry over the past five years has been explosive. Since its invention in the early 1970s, the use of and demand for optical fiber have grown tremendously. The uses of optical fiber today are quite numerous. With the explosion of information traffic due to the Internet, electronic commerce, computer networks, multimedia, voice, data, and video, the need for a transmission medium with the bandwidth capabilities for handling such vast amounts of information is paramount. Fiber optics, with its comparatively infinite bandwidth, has proven to be the solution.

Analysts expect that this industry will continue to grow at a tremendous rate well into the next decade and beyond. Anyone with a vested interest in telecommunication would be all the wiser to learn more about the tremendous advantages of fiber optic communication. With this in mind, this work will provide the student with a rudimentary understanding of fiber optic communication systems, technology, and applications in today’s information world.

 TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION

1.1      BACKGROUND OF THE STUDY

• AIM OF THE STUDY
• OBJECTIVE OF THE STUDY
• SCOPE OF THE STUDY
• APPLICATIONS OF THE STUDY
• USES OF THE STUDY
• BENEFITS OF FIBER OPTICS

CHAPTER TWO

LITERATURE REVIEW

• HISTORICAL BACKGROUND OF THE STUDY
• PARAMETERS OF FIBRE OPTICS IN TRANSMISSION
• COMPARISON WITH ELECTRICAL TRANSMISSION
• TYPES OF FIBER-OPTIC CABLES

CHAPTER THREE

• FIBER OPTIC COMMUNICATION WORKS
• BASIC ELEMENTS OF A FIBER OPTIC COMMUNICATION SYSTEM
• USES OF FIBER OPTICS IN TRANSMISSION
• ADVANTAGES OF FIBER OPTIC TRANSMISSION
• DISADVANTAGES OF FIBER OPTIC TRANSMISSION

CHAPTER FOUR

TESTING

• FIBER OPTIC TESTING
• STARTING A TEST
• VISUAL INSPECTION
• OPTICAL POWER – POWER OR LOSS

CHAPTER FIVE

• CONCLUSION
• REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

An optical fiber is described as a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than electrical cables. Fibers are used instead of metal wires because signals travel along them with less loss; in addition, fibers are immune to electromagnetic interference, a problem from which metal wires suffer excessively [2]. Fibers are also used for illumination and imaging, and are often wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. [3]Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers.[4]

Optical fibers typically include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide.^[5] Fibers that support many propagation paths or transverse modes are called multi-mode fibers, while those that support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a wider core diameter [6] and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters (3,300 ft).

Being able to join optical fibers with low loss is important in fiber optic communication. [7] This is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the fiber cores, and the coupling of these aligned cores. For applications that demand a permanent connection a fusion splice is common. In this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a mechanical splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors.[8]

In communication which is the focus of this study, fiber-optic is used for transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information.^[1] Fiber is preferred over electrical cabling when high bandwidth, long distance, or immunity to electromagnetic interference are required.

Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals. The usage is discussed in this work.

1.1                                           BACKGROUND OF THE STUDY

First developed in the 1970s, fiber-optics have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks in the developed world.

The process of communicating using fiber-optics involves the following basic steps:

1. creating the optical signal involving the use of a transmitter,^[3] usually from an electrical signal
2. relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak
3. receiving the optical signal
4. converting it into an electrical signal

1.2                                                     AIM OF THE STUDY

The main aim of this work is to discuss about the use of optical fibre in communication.

1.3                                              OBJECTIVES OF THE STUDY

At the end of this work, student involved will be able to:

1. Identify the basic components of a fiber optic communication system
2. Discuss light propagation in an optical fiber

• Identify the various types of optical fibers

1. Determine the dispersion characteristics for the various types of optical fibers
2. Describe the various connector types
3. Calculate the power budget for a fiber optic system

1.4                                                   SCOPE OF THE STUDY

Fiber optics is a major building block in the telecommunication infrastructure. Its high bandwidth capabilities and low attenuation characteristics make it ideal for gigabit transmission and beyond. In this study, you will be introduced to the building blocks that make up a fiber optic communication system. This work discuses about the different types of fiber and their applications, light sources and detectors, couplers, splitters, wavelength-division multiplexers, and state-of-the-art devices used in the latest high-bandwidth communication systems. Attention will also be given to system performance criteria such as power and rise-time budgets.

1.5                                          APPLICATIONS OF THE STUDY

1.7                                            LIMITATIONS OF THE STUDY

1.   Transmission over fiber is limited by the attenuation and dispersion.

2.   Multimode fibers may experience:

i.                    Multimode dispersion: The delayed rays cause pulse spreading

ii.                  Chromatic dispersion: Individual wavelengths may travel at different speeds.

3.   Dispersion creates an inherent operational limit defined as a bandwidth-distance product (BDP).

4.   Infrastructure development within cities was relatively difficult and time-consuming, and fiber-optic systems were complex and expensive to install and operate. Due to these difficulties, fiber-optic communication systems have primarily been installed in long-distance applications, where they can be used to their full transmission capacity, offsetting the increased cost.

1.8                                              BENEFITS OF FIBER OPTICS

Optical fiber systems have many advantages over metallic-based communication systems. These advantages include:

1. Long-distance signal transmission: The low attenuation and superior signal integrity found in optical systems allow much longer intervals of signal transmission than metallic-based systems. While single-line, voice-grade copper systems longer than a couple of kilometers (1.2 miles) require in-line signal for satisfactory performance, it is not unusual for optical systems to go over100 kilometers (km), or about 62 miles, with no active or passive processing.
2. Large bandwidth, light weight, and small diameter: Today’s applications require an ever-increasing amount of bandwidth. Consequently, it is important to consider the space constraints of many end users. It is commonplace to install new cabling within existing duct systems or conduit. The relatively small diameter and light weight of optical cable make such installations easy and practical, saving valuable conduit space in these environments.

• Nonconductivity: Another advantage of optical fibers is their dielectric nature. Since optical fiber has no metallic components, it can be installed in areas with electromagnetic interference (EMI), including radio frequency interference (RFI). Areas with high EMI include utility lines, power-carrying lines, and railroad tracks. All-dielectric cables are also ideal for areas of high lightning-strike incidence.

1. Security: Unlike metallic-based systems, the dielectric nature of optical fiber makes it impossible to remotely detect the signal being transmitted within the cable. The only way to do so is by accessing the optical fiber. Accessing the fiber requires intervention that is easily detectable by security surveillance. These circumstances make fiber extremely attractive to governmental bodies, banks, and others with major security concerns.
2. Designed for future applications needs: Fiber optics is affordable today, as electronics prices fall and optical cable pricing remains low. In many cases, fiber solutions are less costly than copper. As bandwidth demands increase rapidly with technological advances, fiber will continue to play a vital role in the long-term success of telecommunication.