This document presents an overview of free space optical communication (FSO). It discusses what FSO is, providing a brief history and explaining how FSO works using lasers or LEDs to transmit data through the air rather than through fiber. The document outlines the benefits of FSO such as high data rates, low cost, and quick installation. It also discusses challenges of FSO including atmospheric effects like fog and limitations on distance. The future of FSO is seen as promising for applications like building-to-building networks but commercial viability remains uncertain due to technical challenges.

1. Free
Space
Optical
Communication
Presented By-
Supriti Guha(L142)
&
Swagata Sharma(L144)
113th April,2017

2. Outline:
 What is FSO?
 History of FSO
 How it works
 Why use FSO?
 Future of FSO
 Application
 Challenges
 Advantages
 Disadvantages
 Conclusion
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3. What is Free Space Optics(FSO)?
 Free Space Optics communication, also called Free Space
Photonics(FSP) or Optical Wireless, refers to the transmission
of visible and infrared (IR) beams through the atmosphere to
obtain optical communication.
 Like fibre, Free Space Optics uses lasers and LED to transmit
data, but instead of enclosing the data stream in a glass fiber,it
is transmitted through the air.
 Free space optical communication is effective means of
communication at high bit rates over short distances.
 Wireless optical holds the promise of delivering data rates
that can meet the broadband requirements.
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4. History of FSO:
 Greeks used sun light for messaging.
 In late nineteenth century Graham Bell demonstrated it.
 Originally developed by the military and NASA.
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5. Block Diagram of FSO:
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7. FSO Transmitter & Receiver
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8. How it works:
 FSO works on simple optical transmission system.
 Provide full duplex (bi-directional) capability.
 Each optical wireless unit uses an optical source, plus a lens or a
telescope.
 Receiving lens or telescope connects to a high-sensitivity
receiver via optical fiber.
 FSO transmits invisible light between two beams. Two beams
are kept narrow.
 FSO can operate into two wavelenths.1.800nm &
2.1550nm.1550 nm wavelengths are more preferred than 800
nm.
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9. Working Diagram:
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10. Why use FSO?
 FSO can send large amounts of data (around 2.5 Gbps of
data).
 No need to get a license, the spectrum used in unlicensed
worldwide.
 Can transmit at distances around 4 km (almost 2 and one
half miles).
 The cost is often less than that of using fiber optic cables.
 FSO system can be installed quickly (in days).
 FSO is used because it uses light there is no RF
interference.
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11.  LAN to LAN connection in a
City,a metropolitan area network.
 Easy to installation.
 High bit rates.
 Low bit error rates.
 Full duplex operation.
 Security.
 Disaster Recovery.
 Last mile Access.
Application:
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12. 1213th April,2017

13. 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
•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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14. Low Clouds, Rain, Snow and Dust:
1.Low Clouds:
•Very similar to fog
•May accompany rain and snow
2.Rain:
•Drop sizes larger than fog and
wavelength of light
•heavy rain can take a link down
3.Heavy Snow:
•May cause ice build-up on windows
•Whiteout conditions
4.Sand Storms:
• Likely only in desert areas; rare
in the urban core
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15. 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.
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16. Advantages of FSO:
 Installation cost is very low as compared to laying Fiber.
 No sunk costs.
 It has very low initial investment.
 Highly secure transmission possible.
 High data rate can be obtained which is comparable to the optical
fibre cable’s data rate but error rate is very low.
 Immunity to electromagnetic interference.
 License free long-range operation ( in contrast with radio
communication).
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17. Disadvantages of FSO:
 Beam dispersion.
 Atmospheric absorption.
 Low power source requires high sensitive receivers.
 Rain.
 Fog (10..~100 dB/km attenuation)
 Snow.
 Pollution/smog.
 Pointing stability in wind.
 Interference from background light source (including the
sun).
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18. Future of FSO:
 The FSO industry shows some strength, and the FSO market is
growing though with much less speed.
 In spite of this, the commercial future of free space optical
communications remains uncertain .Perhaps the best overall
prospects are in space, where progress is being made in improving
acquisition and tracking. Once these are perfected, the bandwidth
advantages of optical free space communications should open up a
substantial market.
 The FSO industry consists of mostly established vendors that
manufacture equipment for various distances and speed of
transmission.The highest speed 2.5Gb/s promises to be increased to
10Gb/s in future.
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19. Conclusion:
 FSO networks can be rapidly deployed to provide immediate
service to the customers.
 Some believe that it may be the unlimited bandwidth solution
for the metro urban core of downtown building-to-building
communication, as well as the optimal technology for home-to-
home and office-to-office connectivity.
 FSO adds the wireless features to the OFC and thus provides
the high bandwidth requirements.
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20. Reference:
 www.freespaceoptics.com
 www.sans.org/reading_room/whitepapers/wireless/free-
space-optics-viable-secure-last-mile-solution_161
 www.fsona.com
 www.pavdata.com
 Free Space Optical Communication Wikipedia_files
 Free Space optics.htm
 Research work and future scope of FSO
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21. Thank You
2113th April,2017