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Free space optics

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Free space optics

  1. 1. Free Space Optics (FSO) BY, YASHCopyright © 2002 Terabeam Corporation. All rights reserved. 1
  2. 2. Presentation Overview • Idea behind Free Space Optics? • Evolution of Free Space Optics? • Why Free Space Optics? • Challenges • Applications • Advantages of FSOCopyright © 2002 Terabeam Corporation. All rights reserved. 2
  3. 3. In the late nineteenth century, Alexander Bell expanded his "phone-phone" communication which was modulated by sunlight.Copyright © 2002 Terabeam Corporation. All rights reserved. 3
  4. 4. In the mid-1960s NASA initiated experiments to utilize the laser as a means of communication between the ground and space.Copyright © 2002 Terabeam Corporation. All rights reserved. 4
  5. 5. Evolution of Free Space OpticsCopyright © 2002 Terabeam Corporation. All rights reserved. 5
  6. 6. Every thing was destroyed including normal fiber link Wall street stock market was closed because the communication was destroyedCopyright © 2002 Terabeam Corporation. All rights reserved. 6
  7. 7. • FSO communication between Merrill Lynch Brokerage and Wall Street in New York following the terrorist attack that destroyed normal fiber optic linkCopyright © 2002 Terabeam Corporation. All rights reserved. 7
  8. 8. Why Free Space Optics? Why Not Just Bury More Fiber? • Cost • Rights of Way • Permits • Trenching(digging) • Time With FSO, especially through the window, no permits, no digging, no feesCopyright © 2002 Terabeam Corporation. All rights reserved. 8
  9. 9. Why Free Space Optics? How Fiber Optic Cable Works Glass Fiber Strands Light Source Detector Detector Light Source Network Network Device Device • Pulses of light communicate the data • “ON” = 1 • “OFF = 0 • Capable of more than 40 GbpsCopyright © 2002 Terabeam Corporation. All rights reserved. 9
  10. 10. Why Free Space Optics? How FSO Works 3 A receiver at the other end of the 2 Transmitter projects the link collects the light using lenses carefully aimed light pulses and/or mirrors into the air 5 Reverse direction data transported the same way. • Full duplex 1 Network traffic 4 Received signal converted into converted back into pulses of invisible fiber or copper and light representing connected to the 1’s and 0’s network Anything that can be done in fiber can be done with FSOCopyright © 2002 Terabeam Corporation. All rights reserved. 10
  11. 11. Why Free Space Optics? Very Narrow and Directional Beams • Beams only a few meters in diameter at a kilometer • Allows VERY close spacing of links without interference • No side lobes • Highly secure • Efficient use of energy • Ranges of 20m to more than 8km possibleCopyright © 2002 Terabeam Corporation. All rights reserved. 11
  12. 12. Why Free Space Optics? Deployment Behind Windows • Rapid installations without trenching and permitting • Direct connection to the end user • Bypasses the building owner – No roof rights – No riser rightsCopyright © 2002 Terabeam Corporation. All rights reserved. 12
  13. 13. 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 equipmentCopyright © 2002 Terabeam Corporation. All rights reserved. 13
  14. 14. Challenges Sunlight Environmental factors Window Attenuation Fog Building Motion Scintillation Alignment Range Obstructions Low Clouds 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. 14
  15. 15. 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 (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 coreCopyright © 2002 Terabeam Corporation. All rights reserved. 15
  16. 16. 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. 16
  17. 17. Application of Free Space Optics 1. Satellite Laser Communication a)Space-to-Ground Lasercom Link b)2000 km Link Distance c)1 Gbps Transmission RateCopyright © 2002 Terabeam Corporation. All rights reserved. 17
  18. 18. 2. Military application of FSO Air Force Navy Its potential for low Secure communication with electromagnetic emanation submerged submarines. when transferring sensitive dataCopyright © 2002 Terabeam Corporation. All rights reserved. 18
  19. 19. Advantages • Wireless communicate from A to B • Low costs ($10K to $20K) • High bit rate (10 Mbps to 2.5 Gbps) • Set up a link in a few days • The lasers used are eye safe, so even a butterfly can fly unscathed through a beamCopyright © 2002 Terabeam Corporation. All rights reserved. 19
  20. 20. Conclusion • FSO is just starting to be applied to solve the Internet “last-mile” interconnectivity problem. • 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 connectivityCopyright © 2002 Terabeam Corporation. All rights reserved. 20
  21. 21. Reference • http://www.lightpointe.com/ • http://www.freespaceoptic.com/ • http://www.fsonews.com/ • http://www.cablefreesolutions.com/ • http://www.thefoa.org/ • http://www.free-space-optics.org/ • http://www.freespaceoptics.com/ • http://www.opticsreport.com/Copyright © 2002 Terabeam Corporation. All rights reserved. 21
  22. 22. Copyright © 2002 Terabeam Corporation. All rights reserved. 22

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