1. Chapter 1 Introduction 4/25/2017 4/25/2017
Course web page contains PowerPoint lecture notes, homework assignments, links to web sites, announcement and other course material.
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2. Introduction
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For years fiber optics has been merely a system for piping light around corners and into in accessible places so as to allow the hidden to be seen. But now, fiber optics has evolved into a system of significantly greater importance and use. Throughout the world it is now being used to transmit voice, video, and data signals by light waves over flexible hair-thin threads of glass or plastics. Its advantages in such use, as compared to conventional coaxial cable or twisted wire pairs, are fantastic. As a result, light-wave communication systems of fiber optics communication system are one of the important feature for today’s communication.
Unit 1 begins with a discussion of the history of fiber optic technology.
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3. 4/25/2017
Unit 1 begins with a discussion of the history of fiber optic technology.
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4. The Nineteenth Century
A History of Fiber Optic Technology
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The Nineteenth Century
John Tyndall, 1870
water and light experiment
demonstrated light used internal reflection to follow a specific path
William Wheeling, 1880
“piping light” patent
never took off
Alexander Graham Bell, 1880
optical voice transmission system
called a photophone
free light space carried voice 200 meters
Fiber-scope, 1950’s
Light
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5. The Twentieth Century core cladding 4/25/2017
Glass coated fibers developed to reduce optical loss
Inner fiber - core
Glass coating - cladding
Development of laser technology was important to fiber optics
Large amounts of light in a tiny spot needed
1960, ruby and helium-neon laser developed
1962, semiconductor laser introduced - most popular type of laser in fiber optics
cladding
core
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6. The Twentieth Century (continued)
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1966, Charles Kao and Charles Hockman proposed optical fiber could be used to transmit laser light if attenuation could be kept under 20dB/km (optical fiber loss at the time was over 1,000dB/km)
1970, Researchers at Corning developed a glass fiber with less than a 20dB/km loss
Attenuation depends on the wavelength of light
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7. Fiber Optics Applications
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Military
1970’s, Fiber optic telephone link installed aboard the U.S.S. Little Rock
1976, Air Force developed Airborne Light Fiber Technology (ALOF)
Commercial
1977, AT&T and GTE installed the first fiber optic telephone system
Fiber optic telephone networks are common today
Research continues to increase the capabilities of fiber optic transmission
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8. Applications of Fiber Optics
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Military
Computer
Medical/Optometric
Sensor
Communication
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9. Military Application
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10. Military Application
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11. Computer Application
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12. Sensors Gas sensors Chemical sensors Mechanical sensors Fuel sensors
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Gas sensors
Chemical sensors
Mechanical sensors
Fuel sensors
Distance sensors
Pressure sensors
Fluid level sensors
Gyro sensors
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13. Medical Application Endoscope Eyes surgery Blood pressure meter
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Endoscope
Eyes surgery
Blood pressure meter
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14. The Future
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Fiber Optics have immense potential bandwidth (over 1 teraHertz, 1012 Hz)
Fiber optics is predicted to bring broadband services to the home
interactive video
interactive banking and shopping
distance learning
security and surveillance
high-speed data communication
digitized video
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15. Fiber Optic Fundamentals
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Fiber Optic Fundamentals
This is a test
This is a bullet
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16. Advantages of Fiber Optics
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Immunity from Electromagnetic (EM) Radiation and Lightning
Lighter Weight
Higher Bandwidth
Better Signal Quality
Lower Cost
Easily Upgraded
Ease of Installation
The main advantages:
Large BW and Low loss
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17. Immunity from EM radiation and Lightning:
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Immunity from EM radiation and Lightning:
- Fiber is made from dielectric (non-conducting) materials, It is un affected by EM radiation.
- Immunity from EM radiation and lightning most important to the military and in aircraft design.
- The fiber can often be run in same conduits that currently carry power, simplifying installation.
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18. Lighter Weight:
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Copper cables can often be replaced by fiber optic cables that weight at least ten times less.
- For long distances, fiber optic has a significant weight advantage over copper cable.
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19. 4/25/2017
Higher Bandwidth
Fiber has higher bandwidth than any alternative available.
CATV industry in the past required amplifiers every thousand feet, when copper cable was used (due to limited bandwidth of the copper cable).
A modern fiber optic system can carry the signals up 100km without repeater or without amplification.
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20. Better Signal Quality
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- Because fiber is immune to EM interference, has lower loss per unit distance, and wider bandwidth, signal quality is usually substantially better compared to copper.
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21. Lower Cost Fiber certainly costs less for long distance applications.
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Fiber certainly costs less for long distance applications.
The cost of fiber itself is cheaper per unit distance than copper if bandwidth and transmission distance requirements are high.
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22. Principles of Fiber Optic Transmission
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Electronic signals converted to light
Light refers to more than the visible portion of the electromagnetic (EM) spectrum
This is my notes
bullet 1
bullet 2
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23. The Electromagnetic Spectrum
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Light is organized into what is known as the electromagnetic spectrum.
The electromagnetic spectrum is composed of visible and near-infrared light like that transmitted by fiber and all other wavelengths used to transmit signals such as AM and FM and television.
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24. Principles of Fiber Optic Transmission
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Wavelength - the distance a single cycle of an EM wave covers
For fiber optics applications, two categories of wavelength are used
visible (400 to 700 nanometers) - limited use
near-infrared (700 to 2000 nanometers) - used almost always in modern fiber optic systems
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25. Electrical-to-Optical Conversion Optical-to-Electrical Conversion
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Fiber optic links contain three basic elements
transmitter
optical fiber
receiver
Optical Fiber
Transmitter
Receiver
User
Input(s)
User
Output(s)
Electrical-to-Optical
Conversion
Optical-to-Electrical
Conversion
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26. Electrical Interface Data Encoder/ Modulator Light Emitter
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Transmitter (TX)
Electrical interface encodes user’s information through AM, FM or Digital Modulation
Encoded information transformed into light by means of a light-emitting diode (LED) or laser diode (LD)
User
Input(s)
Electrical
Interface
Data Encoder/
Modulator
Light
Emitter
Optical
Output
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27. Light Detector/ Amplifier Data Decoder/ Demodulator Electrical
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Receiver (RX)
decodes the light signal back into an electrical signal
types of light detectors typically used
PIN photodiode
Avalanche photodiode
made from silicon (Si), indium gallium arsenide (InGaAs) or germanium (Ge)
the data decoder/demodulator converts the signals into the correct format
Optical
Input
Light Detector/
Amplifier
Data Decoder/
Demodulator
Electrical
Interface
User
Output(s)
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28. Transmission comparison
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Transmission comparison
metallic: limited information and distance
free-space:
large bandwidth
long distance
not private
costly to obtain useable spectrum
optical fiber: offers best of both
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29. Fiber Optic Components
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Fiber Optic Components
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30. 2.3.1 Fiber Optics Cable Extremly thin strands of ultra-pure glass
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Extremly thin strands of ultra-pure glass
Three main regions
center: core (9 to 100 microns)
middle: cladding (125 or 140 microns)
outside: coating or buffer (250, 500 and 900 microns)
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31. A FIBER STRUCTURE
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32. Light Emitters Two types 4/25/2017 Light-emitting diodes (LED’s)
Surface-emitting (SLED): difficult to focus, low cost
Edge-emitting (ELED): easier to focus, faster
Laser Diodes (LD’s)
narrow beam
fastest
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33. Detectors Two types Avalanche photodiode PIN photodiode 4/25/2017
internal gain
more expensive
extensive support electronics required
PIN photodiode
very economical
does not require additional support circuitry
used more often
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34. Interconnection Devices
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Connectors, splices, couplers, splitters, switches, wavelength division multiplexers (WDM’s)
Examples
Interfaces between local area networks and devices
Patch panels
Network-to-terminal connections
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35. Manufacture of Optical Fiber
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Manufacture of Optical Fiber
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36. Introductions
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1970, Corning developed new process called inside vapor deposition (IVD) to first achieve attenuation less than 20dB/km
Later, Corning developed outside vapor deposition (OVD) which increased the purity of fiber
Optical fiber was developed that exhibits losses as low as 0.2dB/km (at 1550nm). This seemed to be adequate for any application.
As the Internet expanded, more capacity was needed. Electronics can handle about 40Gbps, but not much more. Researchers developed Dense Wavelength-Division Multiplexing (DWDM) - 80 or more simultaneous data streams can now be combined on a single fiber, each being transmitted at a slightly different color of light
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37. Manufacture of Optical Fiber - MCVD
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Modified Chemical Vapor Deposition (MCVD)
another term for IVD method
vaporized raw materials are deposited into a pre-made silica tube
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38. Manufacture of Optical Fiber - OVD
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Outside Vapor Deposition (OVD)
vaporized raw materials are deposited on a rotating rod
the rod is removed and the resulting preform is consolidated by heating
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