Fiber optics technician manual 2nd

Fiber optics technician manual 2nd

[...]... fibers, whereas local area networks (LANs) use multimode graded-index fibers Core Buffer Coating Cladding Figure 2-3 Optical fiber construction 18 CHAPTER 2 — BASICS OF FIBER OPTICS Singlemode fibers are smaller in core diameter than multimode fibers and offer much greater bandwidth, but the larger core size of multimode fiber makes coupling to low cost sources such as LEDs much easier Multimode fibers... since all new undersea cables are fiber optics Phone company offices are being interconnected with fiber, and most large office buildings have fiber optic telephone connections into the buildings themselves Only the last links to the home, office, and phone are not fiber CATV also uses fiber optics via a unique analog transmission scheme, but they are already planning on fiber moving to compressed digital... optical fibers are large core step-index multimode fibers, although graded-index plastic fiber is under development Because plastic fibers have a large diameter and can be cut with simple tools, they are easy to work with and can use low-cost connectors Plastic fiber is not used for long distance because it has high attenuation and lower bandwidth than glass fibers However, plastic optical fiber may... Output Figure 2-1 A typical fiber optic data link Cables CHAPTER 2 — BASICS OF FIBER OPTICS Repeater Repeater Fiber Figure 2-2 Repeater Fiber 17 Repeater Fiber Long distance data links require repeaters to regenerate signals In long-distance systems (Figure 2-2) the use of intermediate amplifiers may be necessary to compensate for the signal loss over the long run of the fiber Therefore, long-distance... copper and fiber contingents 31 32 CHAPTER 3 — FIBER OPTIC NETWORKS Security, building management, audio, process control, and almost any other system that requires communications cabling have become available on fiber optics Fiber optics really is the medium of choice for all high bandwidth and/or long-distance communications Let us look at why it is, how to evaluate the economics of copper versus fiber, ... experimented with fiber optics for years, but it was too expensive until the development of the AM analog systems By simply converting the signal from electrical to optical, the advantages of fiber optics became cost-effective Now CATV has adopted a network architecture (Figure 3-2) that overbuilds the normal coax network with fiber optic links 34 CHAPTER 3 — FIBER OPTIC NETWORKS Coax Network Headend Fiber Overbuild... fiber, is corrected in graded-index fiber Longer wavelength goes faster Figure 2-12 Chromatic dispersion occurs because light of different colors (wavelengths) travels at different speeds in the core of the fiber CHAPTER 2 — BASICS OF FIBER OPTICS 27 In an idealized graded-index fiber, all modes have the same group velocity and no modal dispersion occurs But in real fibers, the index profile is a piecewise... inside the core In step-index fiber, the off-axis rays, called “higher-order modes,” bounce 28 CHAPTER 2 — BASICS OF FIBER OPTICS back and forth from core/cladding boundaries as they are transmitted down the fiber Since these higher-order modes travel a longer distance than the axial ray, they are responsible for the dispersion that limits the fiber s bandwidth In graded-index fiber, the reduction of the... moisture d scattering 10 Optical fiber s bandwidth, or information transmission capacity, is limited by two factors: 1 2 C H A P T E R 3 FIBER OPTIC NETWORKS J I M H AY E S A N D P H I L S H E C K L E R One often sees articles written about fiber optic communications networks that imply that fiber optics is “new.” That is hardly the case The first fiber optic telephone network was... tower to be heated and pulled into the required fiber length Target Rod Soot Preform Heat Sources Moving Down Gases Figure 2-7 Vapor axial deposition (VAD) 22 CHAPTER 2 — BASICS OF FIBER OPTICS Coating the Fiber for Protection After the fiber is pulled from the preform, a protective coating is applied very quickly after the formation of the hair-thin fiber (Figure 2-8) The coating is necessary to provide . use singlemode fibers, whereas local area networks (LANs) use multimode graded-index fibers. CHAPTER 2 — BASICS OF FIBER OPTICS 17 Repeater Repeater Repeater Repeater Fiber Fiber Fiber Core Cladding Buffer. three types of optical fiber. Singlemode fibers are smaller in core diameter than multimode fibers and offer much greater bandwidth, but the larger core size of multimode fiber makes cou- pling. much easier. Multimode fibers may be of the step-index or graded-index design. Plastic optical fibers are large core step-index multimode fibers, although graded-index plastic fiber is under development.