ELECTRONIC COMMUNICATIONS A SYSTEMS APPROACH CHAPTER Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Electronic Communications: A Systems Approach Beasley | Hymer | Miller Fiber Optics 16

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Introduction Fiber-optic communications system:  Fiber-optic transmission strand  Source of invisible infrared radiation  Photosensitive detector  Efficient optical connectors at light source

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Introduction Advantages of Optical Communications  Extremely wide system bandwidth  Immunity to electrostatic interference  Elimination of crosstalk  Lower signal attenuation than other systems  Substantially lighter weight and smaller size

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Introduction Advantages of Optical Communications  Lower costs  Safety  Corrosion  Security

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The Nature of Light Refraction of light  Reduction as light passes into denser material; causes light wave to be bent. Speed reduction and refraction different for each wavelength.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The Nature of Light Visible light striking prism  Refraction at both air/glass interfaces; separates light into its various frequencies (colors). Amount of bend by refraction depends on refractive index of two materials involved.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The Nature of Light Infrared light waves  Electromagnetic light waves below frequencies in visible spectrum. Optical spectrum  Frequencies from infrared on up.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The Nature of Light Construction of the Fiber Strand  Core Carries transmitted light.  Cladding Material surrounding core.  Plastic coating surrounds cladding to provide protection.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Fibers Criteria for Choice of Fiber Type  Signal losses, with respect to distance  Ease of light coupling and interconnection  Bandwidth Multimode Step-Index Fiber  Rarely used in telecommunications; very high amounts of pulse dispersion; minimal bandwidth capability.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Fibers Multimode Graded-Index Fiber  Handle higher bandwidths and/or longer lengths of transmission before pulse dispersion effects destroy intelligibility and introduce bit errors.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Fibers Single-Mode Fibers  Accepts only low-order mode allowing operation in high-data-rate, long- distance systems.  Used with high-power, highly directional modulated light sources (laser).

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Fibers Fiber Classification  Telecommunications Industry Association See Table 16-2: Multimode Classifications (by the Refractive Index Profile and Composition)

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 16-2 Multimode Classifications (by the Refractive Index Profile and Composition)

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Fibers Fiber Classification  Telecommunications Industry Association See Table 16-3: Single-Mode Classifications

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 16-3 Single-Mode Classifications

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Fibers Fiber Classification  International Electrotechnical Commission See Table 16-4: Generalized Comparisons of Single-Mode and Multimode Fiber

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 16-4 Generalized Comparisons of Single- Mode and Multimode Fiber

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Fibers Fiber Classification  Plastic Optical Fiber Used in short-range markets.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Fiber Attenuation and Dispersion Attenuation  Loss of power introduced by fiber.  Results from combination of: Scattering, absorption, macrobending, microbending.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Fiber Attenuation and Dispersion Attenuation Dispersion  Pulse broadening; light pulse spreads out in time as it propagates along fiber strand. See Table 16-5: Dispersion Values for Common Optical Wavelengths for Class IVa Fiber

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 16-5 Dispersion Values for Common Optical Wavelengths for Class IVa Fiber

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Fiber Attenuation and Dispersion Dispersion  Modal Predominantly in multimode fiber.  Chromatic Single-mode and multimode fibers.  Polarization mode Single-mode systems.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Fiber Attenuation and Dispersion Dispersion Compensation  Acts like equalizer, negative dispersion canceling positive dispersion.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Components Diode laser (DL)  Source for moderate-band to wideband systems. DL  Source for single-mode fiber; LEDs have low input coupling efficiency. LED  Cheaper; less-complex driving circuitry than DL.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Components Both LEDs and DLs multilayer devices. Light emitted from ED result of recombining of electrons and holes.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Components Modulating the Light Source  Fiber-optic communication Digital pulse systems.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Components Intermediate Components  Isolators  Attenuators  Branching devices  Splitters  Couplers  Wavelength division multiplexers  Optical-line amplifiers

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Components Detectors  Most applications: detector is p-i-n diode.  Avalanche photodiode also used.  Responsivity

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Components Detectors  Dark current  Response speed  Spectral response See Table 16-7: A Comparison of Detectors

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 16-7 A Comparison of Detectors

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Fiber Connections and Splices Optical fiber ultrapure glass; joined in permanent fusion splice or with connector. Fusion splicing  Long-term method; two fibers fused or welded together.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Fiber Connections and Splices Mechanical splices  Permanent/economical choice for fiber- splicing applications. Fiber Connectorization  See Table 16-8: General Fiber Connector Requirements

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 16-8 General Fiber Connector Requirements

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved System Design and Operational Issues Long-haul system  High channel density and bit rate, highly reliable, incorporate redundant equipment, extensive engineering studies. Local-area networks (LANs)  Lower channel capacity and minimal redundance; prespecified and preengineered as to length, bit-rate capability, performance.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved System Design and Operational Issues Dispersion  Single-mode, long-haul, high-bit-rate consideration.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Cabling and Construction Exterior (Outdoor) Installations  Fiber installed Poles, underground in ducts, utility tunnels, direct burial; be aware of exposure. Interior (Indoor) Installations  Environment well controlled.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Cabling and Construction Testing the Fiber Installation  Optical time-domain reflectometer (OTDR) Sends light pulse down fiber; measures reflected light.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Networking Defining Optical Networking  Synchronous optical network (SONET) Standard for long-haul optical transport of telecommunications data. See Table 16-9: SONET Hierarchy Data Rates

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 16-9 SONET Hierarchy Data Rates

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Networking Defining Optical Networking  Fiber to the home (FTTH) Cost-effective way to provide large- bandwidth capabilities to home. See Table 16-10: Ethernet/Fiber Numerics

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table Ethernet/Fiber Numerics

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Optical Networking Air Fiber  Propagation of laser energy through atmosphere, a line-of-sight technique uses parabolic lens to focus laser energy in narrow beam. Fiber Distributed Data Interface  American National Standards Institute (ANSI) developed Fiber Distributed Data Interface (FDDI); utilizes two 100-Mbps token-passing rings.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Safety As light propagates through fiber, factors will attenuate light if there is an open or break. Beware of eye damage. Factors can increase optical power at exposed fiber end.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Safety Safety factors for both fiber optic equipment and the mechanics. In all cases, be sure craft personnel have proper training for the job!

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Troubleshooting You should be able to:  Draw a fiber link showing all components.  Explain the use of the optical power meter.  Describe rise-time measurement.  Troubleshoot fiber-optic data links.