Fort Worth Seminar 2001 - Trafficware Group Inc. · PDF file 1.40 1.60 1.80 2.00 Vacuum Air Water Fused Glass Fused Glass Material The ratio of the speed of light in a vacuum to the

Fiber Optics

Jim Sluss University of Oklahoma

Electrical & Computer Engineering [email protected]

Outline

• Part 1: Fiber Basics • Part 2: Fiber Optic Networks for Traffic and

Transportation Systems • Part 3: Troubleshooting

(Problems, Test & Measurement)

Part 1: Fiber Basics

Basic Communications Link

ChannelSource Transmitter Receiver Destination

Noise Interference

Basic Fiber Transmission Link

Drive Circuit

Signal Restorer

Light Source

AmpPhoto- detector

Transmitter Channel Receiver

Electrical Output Signal

Electrical Input Signal

Attenuation Distortion

Rays of Light Photons

Light is Oscillating Electromagnetic Energy

Smallest Particle of light is called a Photon

A Photon is a quantum or bundle of energy

Only exists if the particle is in motion

Electromagnetic EnergyElectromagnetic Energy

Electromagnetic EnergyElectromagnetic Energy Magnetic

Field

Electric Field

Direction of Propagation

Travels through free space @ 300,000 Km/sec or 186,000 Miles/sec

Consists of Oscillating Electric and Magnetic Waves at right angles to each other

In free space the Velocity of an Electromagnetic Wave is the Speed of Light 300,000 Km/sec

Wavelength

Sine-Wave

Cycle

Frequency (Hertz’s) = The number of Cycles/sec

WavelengthWavelength (Meters) = (Meters) = The distance between the same points on consecutive waves

Positive Amplitude Negative Amplitude

Electromagnetic Waves are Sinusoidal in shape

Electromagnetic EnergyElectromagnetic Energy Magnetic

Field

Electric Field

Direction of Propagation

Travels through free space @ 300,000 Km/sec or 186,000 Miles/sec

Consists of Oscillating Electric and Magnetic Waves at right angles to each other

In free space the velocity of an Electromagnetic Wave is the Speed of Light 300,000 Km/sec

Wavelength

Sine-Wave

Cycle

Frequency (Hertz’s) = The number of Cycles/sec

WavelengthWavelength (Meters) = (Meters) = The distance between the same points on consecutive waves

Positive Amplitude Negative Amplitude

Electromagnetic Waves are Sinusoidal in shape

Wavelength = Velocity

Frequency Wavelength = Meters

Velocity = 300,000Km/Sec.

Frequency = Hertz

What is the wavelength of 60 Hz ?

Wavelength = 300,000 Km 60 Hz

= 5000Km

Los Angeles Boston 5000 Km

60 Hz

QuestionQuestion

Electromagnetic EnergyElectromagnetic Energy Magnetic

Field

Electric Field

Direction of Propagation

Travels through free space @ 300,000 Km/sec or 186,000 Miles/sec

Consists of Oscillating Electric and Magnetic Waves at right angles to each other

In free space the velocity of an Electromagnetic Wave is the Speed of Light 300,000 Km/sec

Wavelength

Sine-Wave

Cycle

Frequency (Hertz’s) = The number of Cycles/sec

WavelengthWavelength (Meters) = (Meters) = The distance between the same points on consecutive waves

Positive Amplitude Negative Amplitude

Electromagnetic Waves are Sinusoidal in shape

Wavelength = Velocity

Frequency Wavelength = Meters

Velocity = 300,000Km/Sec.

Frequency = Hertz

QuestionQuestion What is the wavelength of 2.4 GHz ?

Wavelength = 300,000 Km 2.4 GHz

= 125 microns

Approximately the same diameter as a strand of human hair!

10 0 Sub-sonic

(1 MHz) 10 6 AM Radio

10 4 10 5

(1 KHz) 10 3 Sound 10 2

(1 THz) 10 12

10 8

10 7

(1 GHz) 10 9 Radar

Television

Short-wave Radio FM Radio

10 10 10 11

10 14

10 16 Ultraviolet Rays

Visible Light Infrared Light10 13

10 15

10 22

10 18

10 20

Cosmic Rays

Gamma Rays

X-Rays

10 17

10 19

10 21

Electromagnetic SpectrumElectromagnetic Spectrum High Frequency

Ultra- Short Wavelengths

Low Frequency

Long Wavelengths

Sound

18K Hertz

20 Hertz

Ultra Violet

Violet

Blue

Green

Yellow

Orange

Red

Infrared

400

455

490

550

580

620

750

800

850Far Infrared

Wavelength (nm)

Short

Long

Sight

Electromagnetic SpectrumElectromagnetic Spectrum

Violet Blue Green Yellow Orange RedUltra-Violet Infrared

Invisible Light

400 455 490 550 580 620 750 800

Wavelength (nm)

10 – 9 m

1m

1,000,000,000

1nm =

850 1300 1550

Visible Light

Fiber Optics Transmission

The Speed Of LightThe Speed Of Light

1 1.0003

1.33 1.46 1.48

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

Vacuum Air Water Fused Glass

Fused Glass

Material

The ratio of the speed of light in a vacuum to the speed of light in a specific medium

CoreCladding

IOR

Index of Refraction

Velocity

300,000 Km/s

205,000 Km/s

225,000 Km/s

Journey of LightJourney of Light

InterfaceInterface

GlassGlass I.O.RI.O.R 1.481.48

I.O.RI.O.R 1.461.46

Angle ofAngle of Incidence Incidence

RayRay

Refracted Refracted RayRay

NormalNormal

Angle ofAngle of Incidence Incidence

RayRay

Angle ofAngle of RefractionRefraction

CriticalCritical AngleAngle

Angle ofAngle of IncidenceIncidence

== Angle ofAngle of ReflectionReflection

Advantages of Optical FiberAdvantages of Optical Fiber ••Wide Bandwidth Wide Bandwidth

••Low Loss Low Loss

••Electromagnetic Immunity Electromagnetic Immunity

••Light Weight Light Weight

••Small Size Small Size

••Safety Safety

••Security Security

Flat OC192 129,024 Voice ChannelsFlat OC192 129,024 Voice Channels

Fiber is Dielectric, does not carry electricityFiber is Dielectric, does not carry electricity

0.25dB/Km @ 1550nm0.25dB/Km @ 1550nm

Optical FiberOptical Fiber Two Types Of Fiber -

MultimodeMultimode

SinglemodeSinglemode

• Used for Low Bandwidth (less than 650MHz), Short Haul Communications with distances of up to 3Km (850nm) & 10Km (1300nm)

• Two operating wavelengths, 850nm and 1300nm

• Used for High Bandwidth, Long Haul Communications with distances of up to 40Km (1310nm) and 100Km (1550nm) or more

• Two operating wavelengths at 1310nm and 1550nm

MMultimode & Singlemodeultimode & Singlemode

125 / 62.5 125 / 62.5 micronsmicrons

125 / 62.5 125 / 62.5 micronsmicrons

MultimodeMultimode

CoreCore

FiberFiber BufferBuffer

CladdingCladding

Core / Cladding sizes 50/125, 62.5/125 and 100/140 microns

FDDI Fiber Distributed Data Interface

WavelengthWavelength

850 & 1300nm850 & 1300nm

SinglemodeSinglemode

FiberFiber BufferBuffer

125 / 125 / 9/ 9micronsmicrons

CladdingCladdingCoreCore125 / 125 / 99/ 9micronsmicrons

Core less than 10 microns Cladding 125 micronsWavelengthWavelength

1310 & 1550nm1310 & 1550nm

Attenuation vs. λ

MultimodeMultimode

Refractive Index Profiles

• Multimode Stepped Index Fiber

• Multimode Graded Index Fiber

• Singlemode Stepped Index Fiber

Mode Time Scale

Multimode Stepped Index Fiber

ModalModal

Input Input Output Output Bandwidth Limited to about Bandwidth Limited to about

150Mhz/Km 150Mhz/Km Refractive Refractive

Index Profile Index Profile

Core 100 microns

Cladding 140 microns

Mode Time Scale

Multimode Graded Index Fiber

ModalModal Refractive Refractive

Index Profile Index Profile

Input Input Output Output Bandwidth Limited to Bandwidth Limited to

about 650Mhz/Km about 650Mhz/Km

Signal Distortion Important in determining the information capacity (bandwidth) of an optical fiber as a function of transmission distance.

Intermodal Dispersion Intermodal dispersion - pulse spreading (in time) in multimode fibers, due to varying arrival times at the RX because each mode travels with a slightly different velocity.

core

cladding

cladding

mode 1

mode 2

Axial Cross-Sectio

Refractive Refractive Index Profile Index Profile

Stepped Index, Terahertz Bandwidth Stepped Index, Terahertz Bandwidth

Singlemode Step Index Fiber

Dynamic Range Dynamic Range

Wavelength / Att