Free Space Optics (FSO) Technology Overview
DEPARTEMENT OF MECHANICAL ENGINEERING
BY SHRIKAR PATIL USN-3GN08ME104
Copyright 2002 Terabeam Corporation. All rights reserved.
Presentation Overview
Introduction Why Free Space Optics? How FSO Works Challenges
Advantages of FSO
Applications of FSO
Copyright 2002 Terabeam Corporation. All rights reserved.
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.
Why Free Space Optics?
Why Not Just Bury More Fiber?
Cost
Rights of Way Permits Trenching Time With FSO, especially through the window, no permits, no digging, no fees
Copyright 2002 Terabeam Corporation. All rights reserved.
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.
Why Free Space Optics?
How Fiber Optic Cable Works
Glass Fiber Strands Light Source Detector Network Device Detector Light Source Network Device
Pulses of light communicate the data ON = 1
OFF = 0 Capable of more than 40 Gbps >7 CDs a second
Copyright 2002 Terabeam Corporation. All rights reserved.
How FSO Works
2 Transmitter projects the carefully aimed light pulses into the air
3 A receiver at the other end of the link collects the light using lenses and/or mirrors
5 Reverse direction data transported the same way. Full duplex 1 Network traffic converted into pulses of invisible light representing 1s and 0s 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
Copyright 2002 Terabeam Corporation. All rights reserved.
Challenges
Environmental factors
Fog Building Motion Scintillation Window Attenuation
Sunlight
Alignment
Obstructions
Low Clouds
Range
Each of these factors can attenuate (reduce) the signal. However, there are ways to mitigate each environmental factor.
Copyright 2002 Terabeam Corporation. All rights reserved.
Challenges
Atmospheric 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
Copyright 2002 Terabeam Corporation. All rights reserved.
Challenges
Low 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 (cant 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
Copyright 2002 Terabeam Corporation. All rights reserved.
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Challenges
Scintillation
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.
Copyright 2002 Terabeam Corporation. All rights reserved.
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ADVANTAGES OF FSO
DATA SECURITY: To overcome the security in a network two conditions are necessary 1)Intercept enough of the signal to reconstruct data packet and 2)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 .
Copyright 2002 Terabeam Corporation. All rights reserved.
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Air Force Its potential for low electromagnetic emanation when transferring sensitive data
Navy Secure communication with submerged submarines.
Copyright 2002 Terabeam Corporation. All rights reserved.
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THANK YOU
Copyright 2002 Terabeam Corporation. All rights reserved.
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