Optical Fiber Communications: Principles and Practice (3rd Edition) [John Optical Fiber Communications by Keiser, Gerd(September 10, ) Hardcover. Third Edition. GOVIND E? “Optical Fiber Communications, 2nd Edition” by Gerd Keiser Scilab Code for Optical Fiber Communication by Gerd Keiser. 3rd edition solutions. Sun, 16 Dec GMT gerd keiser optical fiber communications pdf -. Fiber-optic communication is a method of transmitting.
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Fiber-optic communication is a method of 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.
Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals. First developed in the s, fiber-optics have revolutionized the telecommunications industry and have played a major role in kptical advent of the Information Age.
Because of its advantages over electrical transmissionoptical fibers have largely replaced copper wire communications in core networks in the developed world. Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication and cable television signals. Due to herd lower attenuation and interferenceoptical fiber has large advantages over existing copper wire in long-distance, high-demand applications.
However, 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 herd systems have primarily been installed in long-distance applications, where they can be used commnications their full transmission capacity, offsetting the increased cost.
The prices of fiber-optic communications have dropped considerably since The price for rolling out fiber to the home has currently become more cost-effective than that of rolling out a copper based network. Sincewhen optical-amplification systems became commercially available, the telecommunications industry has laid a vast network of intercity and transoceanic fiber communication lines.
Bell considered it his most important invention. The device allowed for the transmission of sound on a beam of light.
Optical Fiber Communications by Gerd Keiser
On June 3,Bell conducted the world’s first wireless telephone transmission between ciber buildings, some meters apart. The Photophone’s first practical use came in military communication systems many decades later. In Harold Hopkins and Narinder Singh Kapany showed that rolled fiber glass allowed light to be transmitted.
Initially it was considered that the light can traverse in only straight medium. Jun-ichi Nishizawaa Japanese scientist at Tohoku Universityproposed the use of optical fibers for communications in meiser In Charles K. After a period of research starting fromthe first commercial fiber-optic communications system was developed which operated at a wavelength around 0.
The second editioj of fiber-optic communication was developed for commercial use in the early s, operated at 1. These early systems were initially limited by multi mode fiber dispersion, and in the single-mode fiber was revealed to greatly improve system performance, however practical connectors capable of working with single mode fiber proved difficult to develop. Inthey had already developed a fiber optic cable that would help further their progress toward making fiber optic cables that would circle the globe.
The first transatlantic telephone cable to use optical fiber was TAT-8based on Desurvire optimised laser amplification technology. It went into operation in Third-generation fiber-optic systems operated at 1. This development was spurred by the discovery of Indium gallium arsenide and the development of the Indium Gallium Arsenide photodiode by Pearsall. Engineers overcame earlier difficulties with pulse-spreading at that wavelength using conventional InGaAsP semiconductor lasers.
Scientists overcame this difficulty by using dispersion-shifted fibers designed to have minimal dispersion at 1. These developments eventually allowed third-generation systems to operate commercially at 2.
The fourth generation of fiber-optic communication commnications used optical amplification to reduce the need for repeaters and wavelength-division multiplexing to increase data capacity. The focus of development for the fifth 3rdd of fiber-optic communications is on extending the wavelength range over which a WDM system can operate.
The conventional wavelength window, known as the C band, covers the wavelength range 1. Other developments include the concept of ” optical solitons “, pulses that preserve their shape by counteracting the effects of dispersion with communicatiosn nonlinear effects of the fiber by using pulses of a specific shape.
In the late s throughindustry promoters, and research companies such as KMI, and RHK predicted massive increases in demand for communications bandwidth due to increased use of the Internetand commercialization of various bandwidth-intensive consumer services, commubications as video on demand. Internet protocol data traffic was increasing exponentially, at a faster rate than integrated circuit complexity had increased under Moore’s Law. From the bust of the dot-com bubble throughhowever, the main trend in the industry has been consolidation of firms and offshoring editlon manufacturing to reduce costs.
Modern fiber-optic communication systems generally include an optical transmitter to convert an electrical signal into an optical signal to send through the optical fiber, a cable containing bundles of multiple optical fibers that is routed through underground conduits edltion buildings, multiple kinds of amplifiers, and an optical receiver to recover the signal as an electrical signal.
The information transmitted is typically digital information generated by computers, telephone systems and cable television companies.
The most commonly used optical transmitters are semiconductor devices such as light-emitting diodes LEDs and laser diodes. The difference between LEDs and laser diodes is that LEDs produce incoherent lightwhile laser diodes produce coherent light. For use in optical communications, semiconductor optical transmitters must be designed to be compact, efficient and reliable, while operating in an optimal wavelength range and directly modulated at high frequencies.
In its simplest form, an LED is a forward-biased p-n junctionemitting light through spontaneous emissiona dommunications referred to as electroluminescence. However, due 3d their relatively simple design, LEDs are very useful for low-cost applications.
The large spectrum width of LEDs is subject to higher fiber dispersion, considerably limiting their bit rate-distance product a common eedition of usefulness. LEDs have also been developed that use several quantum wells to emit light at different wavelengths over a broad spectrum and are currently in use for local-area WDM Wavelength-Division Multiplexing networks.
The narrow spectral width also allows for high bit rates since it reduces the effect of opptical dispersion. Furthermore, semiconductor lasers can be modulated directly at high frequencies because of short recombination time.
Laser diodes are often directly modulatedthat is the light output is controlled by a current applied directly to the device.
gerd keiser optical fiber communications 3rd edition
For very high data rates or very long distance linksa laser source may be operated continuous waveand the light modulated by an external device, an optical modulatorsuch as an electro-absorption modulator or Mach—Zehnder interferometer. External modulation increases the achievable link distance by eliminating laser chirpwhich broadens the linewidth of directly modulated lasers, increasing the chromatic dispersion in the fiber.
A transceiver is a device combining a transmitter and a receiver in a single housing see picture on right. Fiber optics have seen recent advances in technology. The main component of an optical receiver is a photodetector which converts light into electricity using the photoelectric effect. The primary photodetectors for telecommunications are made from Indium gallium arsenide The photodetector is typically a semiconductor-based photodiode.
Several types of photodiodes include p-n photodiodes, p-i-n photodiodes, and avalanche photodiodes. Metal-semiconductor-metal MSM photodetectors are also used due to their suitability for circuit integration in regenerators and wavelength-division multiplexers.
Optical-electrical converters are typically coupled with a transimpedance amplifier and a limiting amplifier to produce a digital signal in the electrical domain from the incoming optical signal, which may be attenuated and distorted while passing through the channel.
Further signal processing such as clock recovery from data CDR performed by a phase-locked loop may also be applied before the data is passed on. An optical communication system transmitter consists of a digital-to-analog converter DACa driver amplifier and a Mach—Zehnder-Modulator.
Digital predistortion counteracts the degrading effects and enables Baud rates up to 56 GBaud and modulation formats like 64 QAM and QAM with the commercially available components. The transmitter digital signal processor performs digital predistortion on the input signals using the inverse transmitter model before uploading the samples to the DAC.
Older digital predistortion methods only addressed linear effects. Recent publications also compensated for non-linear distortions. Berenguer et al models the Mach—Zehnder modulator as an independent Wiener system and the DAC and the driver amplifier are modelled by a truncated, time-invariant Volterra series. Duthel et al records for each branch of the Mach-Zehnder modulator several signals at different polarity and phases. The signals are used to calculate the optical field.
Cross-correlating in-phase and quadrature fields identifies the timing skew. The frequency response and the non-linear effects are determined by the indirect-learning architecture. An optical fiber cable consists of a core, claddingand a buffer a protective outer coatingin which the cladding guides the light along the core by using the method of total internal reflection.
The core and the cladding which has a lower- refractive-index are usually made of high-quality silica glass, although they can both be made of plastic as well. Connecting two optical fibers is done by fusion splicing or mechanical splicing and requires special skills and interconnection technology due to the microscopic precision required to align the fiber cores. Two main types of optical fiber used in optic communications include multi-mode optical fibers and single-mode optical fibers.
However, a multi-mode fiber introduces multimode distortionwhich often limits the bandwidth and length of the link. Furthermore, because of its higher dopant content, multi-mode fibers are usually expensive and exhibit higher attenuation.
Both single- and multi-mode fiber is offered in different grades. In order to package fiber into a commercially viable product, it typically is protectively coated by using ultraviolet UVlight-cured acrylate polymersthen terminated with optical fiber connectorsand finally assembled into a cable.
After that, it can be laid in the ground and then run through the walls of a building and deployed aerially in a manner similar to copper cables. These fibers require less maintenance than common twisted pair wires once they are deployed.
Specialized cables are used for long distance subsea data transmission, e. New — cables operated by commercial enterprises Emerald AtlantisHibernia Atlantic typically have four strands of fiber and cross the Atlantic NYC-London in 60—70ms.
Another common practice is to bundle many fiber optic strands within long-distance power transmission cable. This exploits power transmission rights of way effectively, ensures a power company can own and control the fiber required to monitor its own devices and lines, is effectively immune to tampering, and edtiion the deployment of smart grid technology. The transmission distance of a fiber-optic communication system has comminications been limited by fiber attenuation and by fiber distortion.
By using opto-electronic repeaters, these problems have been eliminated. These repeaters convert the signal into an electrical signal, and then use a transmitter to send the signal again at a higher intensity than was received, thus counteracting the loss incurred ciber the previous segment.
An alternative approach is to use optical amplifiers which amplify the optical signal directly without having to comnunications the signal to the electrical domain. Optical amplifiers have several significant advantages over electrical repeaters. First, an optical amplifier opttical amplify a very wide band at once which can include hundreds of individual channels, eliminating the need to demultiplex DWDM signals at each amplifier. Second, optical amplifiers operate independently of the data rate and modulation format, enabling multiple data rates and modulation formats to co-exist and enabling upgrading of the data rate of a system without having to replace all of the repeaters.
Third, optical amplifiers are much simpler than a repeater with the same capabilities and are therefore significantly more reliable. Optical amplifiers have largely replaced repeaters in new installations, although electronic repeaters are still widely used as transponders for wavelength conversion.
Wavelength-division ccommunications WDM is the practice of multiplying the available capacity of optical fibers through use of parallel channels, each channel on a dedicated 3rdd of light. This requires a wavelength division multiplexer in the transmitting equipment and a demultiplexer iptical a spectrometer in the receiving equipment.
Arrayed waveguide gratings are commonly used for multiplexing and demultiplexing in WDM. Using WDM technology now commercially available, the bandwidth of a fiber can be divided into as many as channels  to support a combined bit rate in the range of 1. This value is a product of bandwidth and distance because there is a trade-off between the bandwidth of the signal and the distance over which it can be carried.
Engineers are always looking at current limitations in order to improve fiber-optic communication, and several of these restrictions are currently being researched.