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Copyright © 2002 Terabeam Corporation. All rights reserved. 1
Free Space Optics (FSO)Technology OverviewFree Space Optics (FSO)Technology Overview
DEPARTEMENT OF MECHANICAL ENGINEERING
BY SHRIKAR PATIL
USN-3GN08ME104
Copyright © 2002 Terabeam Corporation. All rights reserved. 2
Presentation OverviewPresentation Overview
• IntroductionIntroduction
• Why Free Space Optics?Why Free Space Optics?
• How FSO WorksHow FSO Works
• ChallengesChallenges
• Advantages of FSOAdvantages of FSO
• Applications of FSOApplications of FSO
Copyright © 2002 Terabeam Corporation. All rights reserved. 3
INTRODUCTION INTRODUCTION
• Free space optics is line of sight technology which uses laser and photo detector to provide optical connection between two system without fiber.
• FSO can transmit data ,audio and video at the speed of 2.5GHz.
• FSO uses invisible infrared laser light with wavelength of 750nm or 1500nm..
• FSO is full duplex(It can transmit data in both direction).
Copyright © 2002 Terabeam Corporation. All rights reserved. 4
Why Free Space Optics?Why Not Just Bury More Fiber?Why Free Space Optics?Why Not Just Bury More Fiber?
• Cost
• Rights of Way
• Permits
• Trenching
• Time
With FSO, especially through With FSO, especially through the window, no permits, no the window, no permits, no
digging, no fees digging, no fees
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Why Free Space Optics?The FSO “Value Proposition”Why Free Space Optics?The FSO “Value Proposition”
• No interference
• Unlicensed
• Easy to install
• Through the window (or from the rooftop)
• No trenching, no permits
• Fiber-like data rates
• Many deployment options
• Fungible equipment
Copyright © 2002 Terabeam Corporation. All rights reserved. 6
Why Free Space Optics?How Fiber Optic Cable WorksWhy Free Space Optics?How Fiber Optic Cable Works
Light Source
Glass Fiber Strands
Detector
NetworkDevice
• Pulses of light communicate the data
• “ON” = 1
• “OFF = 0
• Capable of more than 40 Gbps
• >7 CDs a second
Light Source
Detector
NetworkDevice
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How FSO WorksHow FSO Works
1 Network traffic converted into pulses of invisible light representing 1’s and 0’s
2 Transmitter projects the carefully aimed light pulses into the air
5 Reverse direction data transported the same way.
• Full duplex
3 A receiver at the other end of the link collects the light using lenses and/or mirrors
4 Received signal converted back into fiber or copper and connected to the network
Anything that can be done in fiber can be done with FSO
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ChallengesEnvironmental factorsChallengesEnvironmental factors
Sunlight
Building Motion
Alignment
WindowAttenuation
Fog
Each of these factors can “attenuate” (reduce) the signal. However, there are ways to mitigate each environmental factor.
Scintillation
RangeObstructions
Low Clouds
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ChallengesAtmospheric Attenuation - FOGChallengesAtmospheric Attenuation - FOG
• Absorption or scattering of optical signals due to airborne particles
• Primarily FOG but can be rain, snow, smoke, dust, etc.
• Can result in a complete outage
• FSO wavelengths and fog droplets are close to equal in size
– (Mie Scattering)
• Typical FSO systems work 2-3X further than the human eye can see
• High availability deployments require short links that can operate in the fog
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ChallengesLow Clouds, Rain, Snow and Dust
ChallengesLow Clouds, Rain, Snow and Dust • Low Clouds
– Very similar to fog
– May accompany rain and snow
• Rain– Drop sizes larger than fog and wavelength of
light
– Extremely heavy rain (can’t see through it) can take a link down
– Water sheeting on windows
• Heavy Snow– May cause ice build-up on windows
– Whiteout conditions
• Sand Storms– Likely only in desert areas; rare in the urban
core
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• Beam spreading and wandering due to propagation through air pockets of varying temperature, density, and index of refraction.
• Almost mutually exclusive with fog attenuation.
• Results in increased error rate but not complete outage.
ChallengesScintillationChallengesScintillation
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ADVANTAGES OF FSO
• DATA SECURITY: To overcome the security in a network two conditions are necessary1)Intercept enough of the signal to reconstruct data packet and2)Be able to decode that information.
• NO LICENCE REQUIRE
• INSTALLATION COST IS VERY LOW
• HIGHLY SECURED TRANSMISSION IS POSSIBLE
• HIGH DATA RATE UPTO 2.5 GHz TO 10 GHz IN NEARER FUTURE .
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Air Force Its potential for low
electromagnetic emanation when transferring sensitive data
Navy Secure communication
with submerged submarines.
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THANK YOU
