Optical fibre communication pdf

 

    Main Characteristics of Fiber Optics Communication System. - Light propagation in of Plastic Fibers. (Source: stansaturtowi.ga). Identify the basic components of a fiber optic communication system. • Discuss light propagation in an optical fiber. • Identify the various types of optical fibers. PDF | Optical Fiber Communication-An Introduction | ResearchGate, the professional network for scientists.

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    Optical Fibre Communication Pdf

    Fiber optic data transmission systems send information over fiber by turning electronic signals into light. ❑ Light refers to more than the portion of the. Element of an Optical Fiber Transmission link. Basic block diagram of optical fiber communication system consists of following important blocks. 1. Transmitter. 2. image, and the first application of optical fibers to imaging was conceived. development of optical fiber communications was primarily a materials one—it was.

    The digital communication techniques discussed so far have led to the advancement in the study of both Optical and Satellite communications. Let us take a look at them. Fiber Optics An optical fiber can be understood as a dielectric waveguide, which operates at optical frequencies. The device or a tube, if bent or if terminated to radiate energy, is called a waveguide, in general. Following image depicts a bunch of fiber optic cables. The electromagnetic energy travels through it in the form of light. The light propagation, along a waveguide can be described in terms of a set of guided electromagnetic waves, called as modes of the waveguide. Working Principle A fundamental optical parameter one should have an idea about, while studying fiber optics is Refractive index. The bent of light ray at the interface is the result of difference in the speed of light in two materials that have different refractive indices. The incident angle and refracted angle are shown in the following figure. Further refraction is not possible beyond this point. The following figure shows these terms clearly. A light ray, if passed into a glass, at such condition, it is totally reflected back into the glass with no light escaping from the surface of the glass.

    Transparent glass or plastic fibers which allow light to be guided from one end to the other with minimal loss. Fiber optic cable functions as a "light guide," guiding the light introduced at one end of the cable through to the other end.

    The light source can either be a light-emitting diode LED or a laser. The light source is pulsed on and off, and a light-sensitive receiver on the other end of the cable converts the pulses back into the digital ones and zeros of the original signal. Even laser light shining through a fiber optic cable is subject to loss of strength, primarily through dispersion and scattering of the light, within the cable itself.

    The faster the laser fluctuates, the greater the risk of dispersion. Light strengtheners, called repeaters, may be necessary to refresh the signal in certain applications.

    While fiber optic cable itself has become cheaper over time - a equivalent length of copper cable cost less per foot but not in capacity.

    Fiber optic cable connectors and the equipment needed to install them are still more expensive than their copper counterparts. Single Mode cable is a single stand most applications use 2 fibers of glass fiber with a diameter of 8. Single Mode Fiber with a relatively narrow diameter, through which only one mode will propagate typically or nm.

    Carries higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width. Synonyms mono-mode optical fiber, single-mode fiber, single-mode optical waveguide, uni-mode fiber. Single Modem fiber is used in many applications where data is sent at multi-frequency WDM Wave-Division-Multiplexing so only one cable is needed - single-mode on one single fiber Single-mode fiber gives you a higher transmission rate and up to 50 times more distance than multimode, but it also costs more.

    Single-mode fiber has a much smaller core than multimode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fiber cable type. Single-mode optical fiber is an optical fiber in which only the lowest order bound mode can propagate at the wavelength of interest typically to nm.

    Most applications in which Multi-mode fiber is used, 2 fibers are used WDM is not normally used on multi-mode fiber. POF is a newer plastic-based cable which promises performance similar to glass cable on very short runs, but at a lower cost.

    Optical Fiber Communication Technology and System Overview

    Multimode fiber gives you high bandwidth at high speeds 10 to MBS - Gigabit to m to 2km over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically or nm.

    Typical multimode fiber core diameters are 50, However, in long cable runs greater than feet [ Today's optical fiber attenuation ranges from 0. Attenuation limits are based on intended application.

    Optical Fiber Communication Technology and System Overview

    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 systems used optical amplification to reduce the need for repeaters and wavelength-division multiplexing to increase data capacity.

    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 the nonlinear effects of the fiber by using pulses of a specific shape. In the late s through , industry promoters, and research companies such as KMI, and RHK predicted massive increases in demand for communications bandwidth due to increased use of the Internet , and commercialization of various bandwidth-intensive consumer services, such 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 through , however, the main trend in the industry has been consolidation of firms and offshoring of manufacturing to reduce costs. Technology[ edit ] 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 and 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. Transmitters[ edit ] A GBIC module shown here with its cover removed , is an optical and electrical transceiver. The electrical connector is at top right and the optical connectors are at bottom left 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 light , while 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 junction , emitting light through spontaneous emission , a phenomenon referred to as electroluminescence. However, due to 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 measure 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 chromatic dispersion. Furthermore, semiconductor lasers can be modulated directly at high frequencies because of short recombination time.

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    Optical Fiber Communication - OFC Study Materials | PDF FREE DOWNLOAD

    IEE , — Google Scholar. Kapron, F. Hayashi, I. Jacobs, Ira Fiber-optic transmission and system evolution, in T.

    Bartee ed , Digital Communications, Howard W. Gloge, D. Olshansky, R. Optics, 15 — Gloge, D, Marcatili, E. Miller and A. Namihira, Y. Jones, W.

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