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2009 | Buch

Fiber Optic Communications: A Review Kapitel lesen Erstes Kapitel lesen

Fiber Optics Engineering

verfasst von: Mohammad Azadeh

Verlag: Springer US

Buchreihe : Optical Networks

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

Within the past few decades, information technologies have been evolving at a tremendous rate, causing profound changes to our world and our ways of life. In particular, fiber optics has been playing an increasingly crucial role within the telecommunication revolution. Not only most long-distance links are fiber based, but optical fibers are increasingly approaching the individual end users, providing wide bandwidth links to support all kinds of data-intensive applications such as video, voice, and data services. As an engineering discipline, fiber optics is both fascinating and challenging. Fiber optics is an area that incorporates elements from a wide range of techno- gies including optics, microelectronics, quantum electronics, semiconductors, and networking. As a result of rapid changes in almost all of these areas, fiber optics is a fast evolving field. Therefore, the need for up-to-date texts that address this growing field from an interdisciplinary perspective persists. This book presents an overview of fiber optics from a practical, engineering perspective. Therefore, in addition to topics such as lasers, detectors, and optical fibers, several topics related to electronic circuits that generate, detect, and process the optical signals are covered. In other words, this book attempts to present fiber optics not so much in terms of a field of “optics” but more from the perspective of an engineering field within “optoelectronics.

Inhaltsverzeichnis

Frontmatter
Chapter 1. Fiber Optic Communications: A Review
There is no doubt that telecommunication has played a crucial role in the makeup of the modern world. Without the telecommunication revolution and the electronic foundations behind it, the modern life would be unimaginable. It is not hard to imagine why this is the case, after all, it is communication that shapes us as human beings and makes the world intelligible to us. Our daily life is intricately intertwined with telecommunication and its manifestations. While we are driving, we call our friend who is traveling on the other side of the world. We can watch events live as they are unfolding in another continent. We buy something in Australia and our credit card account is charged in United States. We send and receive emails with all kinds of attachments in a fraction of second. In short, under the effects of instant telecommunications, the world is shrinking from isolated lands separated by vast oceans to an interconnected global village.
Mohammad Azadeh
Chapter 2. Communication Networks
In the previous section we reviewed the basic blocks that make up a fiber optic system. We divided a link vertically into two domains: the processing layers and the physical layer. The function of the physical layer is to convert an electrical signal into an optical signal, transmit the optical signal through the fiber, and convert it back to an electrical signal at the receiver. The performance of a physical layer system can be measured by the signal fidelity at the receiver end, i.e., by comparing the regenerated electrical signal at the receiver to the original electrical signal at the transmitter.
Mohammad Azadeh
Chapter 3. Signal Characterization and Representation
Fiber optic systems utilize the wide bandwidth of the fiber to transfer very high data rates over long distances. As noted in Chapter 1, in order to represent information, a physical quantity must be modulated. A “signal” is the representation of information, and a physical signal is realized when a voltage, a current, or an electromagnetic wave is modulated. In fiber optics, we deal with electrical and optical signals. At the level of physical layer, a fiber optic link converts an electrical signal to an optical signal, transmits it over the fiber, and converts it back to an electrical signal at the other side.
Mohammad Azadeh
Chapter 4. Semiconductor Lasers
In this chapter we discuss the basic principles of operation of semiconductor lasers. These devices are by far the most common optical source in fiber optic communication. Properties such as high-speed modulation capability, high efficiency, wavelengths in the infrared communication band, small size, and high reliability make these devices an indispensable part of fiber optic links. This chapter starts with the theory of light amplifiers and oscillators. Next we discuss optical amplification in semiconductors, which is the basis of semiconductor lasers. We will also introduce the rate equations, which are an essential tool in understanding the behavior of semiconductor lasers. Next we will study various properties of these lasers, both in frequency and in time domains. Finally, we will review some of the practical semiconductor devices in use.
Mohammad Azadeh
Chapter 5. Optical Fibers
The revolution in fiber optic communication has been made possible by technological advancements that have resulted in the availability of low-loss silica fibers. The attenuation in a single-mode fiber can be as low as 0.25 dB/km. This allows for the propagation of optical signals for long distances without the use of repeaters or amplifiers. In this chapter we will discuss different types of fibers commonly used in fiber optic communication, as well as the parameters that affect light coupling into the fiber.
Mohammad Azadeh
Chapter 6. PIN and APD Detectors
As mentioned in Chapter 1, in a fiber optic link an optical source, such as semiconductor laser, converts an electrical signal to an optical signal. The optical signal, once coupled properly into an optical fiber, can travel as a guided wave for relatively long distances. At destination, the optical signal must be converted back from the optical domain to the electrical domain. This conversion is accomplished by using a photodetector, which is a light-sensitive device that converts the received photons into electrons.
Mohammad Azadeh
Chapter 7. Light Coupling and Passive Optical Devices
In electrical circuits, passive components refer to resistors, capacitors, and inductors; elements that overall consume power. On the other hand, active components deliver power to a system. In fiber optic systems, passive components typically refer to those that are not involved in opto-electric conversion, i.e., they neither generate nor detect light. Instead they are involved in guiding or manipulating the light without adding energy to it.
Mohammad Azadeh
Chapter 8. Optical Transmitter Design
In this chapter we discuss design issues related to optical transmitters. An optical transmitter acts as the interface between the electrical and optical domains by converting electrical signals to optical signals. For digital transmitters, the optical output must conform to specifications such as optical power, extinction ratio, rise and fall time, and jitter. In analog transmitters, the optical output must faithfully regenerate the input in terms of linearity, bandwidth, phase delay, etc. It is the responsibility of the designer to ensure that the transmitter meets all the relevant requirements for the intended application of the design.
Mohammad Azadeh
Chapter 9. Optical Receiver Design
In this chapter we consider issues related to the design of optical receivers. As signals travel in a fiber, they are attenuated and distorted, and it is the function of the receiver circuit at the other side of the fiber to generate a clean electrical signal from this weak, distorted optical signal.
Mohammad Azadeh
Chapter 10. Reliability
Reliability is a critical concern in all engineering systems. Reliability issues present significant challenges to the designers, because usually it is hard to predict them in advance. As a result, oftentimes problems associated with reliability show up later in the design phase. Moreover, the inherent statistical nature of failures makes them harder to understand and deal with. From an economic perspective, reliability issues are often very expensive, because they expose problems late in the design phase, or even when the systems are deployed and are under normal operation. Such failures may require costly and time consuming maintenance, debugging, or recalls.
Mohammad Azadeh
Chapter 11. Test and Measurement
This chapter deals with measurement and characterization of the critical parameters for fiber optic devices and links. These parameters include quantities such as optical power, extinction ratio, rise and fall time, bit error rate, wavelength, and spectral width. Measurement methods are crucial for evaluation of existing devices and systems as well as for validation and debugging of new designs. Without accurate test and measurement methods, the critical relationship between theory and real world breaks down, effectively rendering most engineering efforts meaningless.
Mohammad Azadeh
Chapter 12. Standards
We started Chapter 1 with an example of spoken language as an intuitive model of a communication link. In language, a complex set of conventions and rules are at work to ensure that the sounds made by one side are interpreted correctly by the other side, so that the intended message is conveyed and communication is established. The role of standards in telecommunication is fundamentally not so different. However, fiber optic standards are not limited to those that cover communication aspects. There are also a wide range of standards related to components, systems, measurements, and test methodologies. Moreover, standards are constantly evolving as a result of new technologies, new needs, and new problems. This makes the topic of standards a vast, complex subject, especially in an area such as fiber optics which involves many different fields and technologies.
Mohammad Azadeh
Backmatter
Metadaten
Titel
Fiber Optics Engineering
verfasst von
Mohammad Azadeh
Copyright-Jahr
2009
Verlag
Springer US
Electronic ISBN
978-1-4419-0304-4
Print ISBN
978-1-4419-0303-7
DOI
https://doi.org/10.1007/978-1-4419-0304-4

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