1. WHAT IF I TRANSMIT LIGHT WITHOUT OPTICAL FIBRE?
Powerpoint Templates

2. FREE SPACE OPTICS (F.S.O.)
PRESENTED BY : VIVEK SHRIVASTAV
BRANCH/YEAR :- E&c ENGG.,4TH YEAR
SECTION :- ‘B’

3. Contents :- Introduction Various configurations
Indoor and outdoor implementations
Various attenuation factors
Advantages and Disadvantages
Present usages of technology
future scope with technology
Conclusion
references

4. In F.S.O. \ INTRODUCTION:- FIBRE REPLACED BY FREE SPACE
INFORMATION TARNSMISSION BY LIGHT BEAMS THROUGH THE ATMOSPHERE

5. ‘Wireless’ does not imply roaming
‘Ofc’ v/s ‘fso’
‘Wireless’ does not imply roaming

6. Various config. :- Mainly Three types of configuration is there:-
Line of site(LOS) config.
Directed-non LOS config. Hybrid config.
Non Directed-non LOS config. Diffused config.

7. Indoor implementation:-
Interference:-
Incandescent light(~2800 K) max. attenuation.
Sunlight (~6000K)
Florescent lamp
Attenuation :-
Free space loss(due to beam divergence) –impo.
Atmospheric loss (not much in indoors)
Eye safety:-most important
should be class 1 safe(< 0.5 mW, 880 nm, LASER)
restricts system power (though LEDs can be used at higher powers, but Bandwidth limited)

8. Outdoor implementation :-
Attenuation – Most Important
Atmospheric Loss (varies with weather)
0.2 dB/km in exceptionally clear weather
300 dB/km in very dense fog
Restricts the range (~500m in most commercial systems)
May need low capacity back-up RF links
Scintillation Noise (atmospheric turbulence induced intensity fluctuations) – speckled pattern
Alignment Issues – Line of sight
Interference
Sunlight (~ 6000 K)

9. Various Attenuation factors :-

10. Attenuation factors ….contd.
PR= PT . Areceiver . e –σ.R/(Div-range)2
PR ~ PT e –σ.R
WHERE σ IS ATTENUATION FACTOR FOR TRANSMISSION
Free Space losses-beam divergence
Atmospheric losses exponential term– dominates
Scattering + Absorption

11. Thus, larger λ => lower attenuation
Attenuation :: Scattering
Depends on particle size
Size parameter α = 2π r/λ
‘ r ’ varies with atmospheric composition
r << λ => σ ~ λ Rayleigh Scattering-fog
r ~ λ => σ ~ λ-1.6 to 0 Mie Scattering
r >> λ => σ ~ λ Geometric Scattering
Thus, larger λ => lower attenuation

12. Scintillation noise :-
Inhomogenities in Temp. and Pressure
Variations in Refractive Index along the transmission path
Speckled pattern (both in time and space) at the receiver

13. Link capacity:- Advantages of FSO :-
capable of sending up to 1.25 Gbps of data, voice, and video communications simultaneously through the air
enables optical communications at the speed of light
full-duplex Gigabit Ethernet throughout
WDM(wavelength division multiplexing) leading upto 10Gbps connectivity.

14. Economical :- Advantages …….. Contd.
Uses optical transceiver-cheaper
No licensing for spectrum-bandwidth allocation is free
Requires no software upgradation –for particular device
Immune to radio frequency interference and saturation.

15. Advantages …… Contd.
Simpler to install-just connecting the to transceiver.
High bit rates.
low bit error rates
Protocol transparency-using highly directional beam.
easy to encrypt any data travelling across the FSO connection

16. Disadvantages of FSO :-
Beam dispersion-atmospheric effect.
Atmospheric absorption
Fog -one of major cause.
Scintillation
Sun at opposite side to receiver-swamp signals.
Shadowing .

17. Disadvantage…….. Contd. Requires a compatible area for installation.
Devices require maintenance.

18. Application-FSO :-
LAN-to-LAN connections on campuses at Fast Ethernet or Gigabit Ethernet speeds
LAN-to-LAN connections in a city- Metropolitan area network.
Converged Voice-Data-Connection
Temporary network installation (for events or other purposes).
Re-establish high-speed connection quickly (disaster recovery).

19. Application-FSO :- ..Contd.
For communications between spacecraft, including elements of a satellite constellation.
As option for intra connectivity in companies.

20. Future scope of technology:-
Deep space exploration.
High speed switching systems.
Analogous to satellite communication link.
Will reduce the effective cost of means of communications.

21. Some snaps-FSO :-

22. Conclusions :- Short distance connectivity.
Atmospheric condition dependency.
Higher speed and bandwidth.
Immune to data loss.
Highly secure.
Fast temporary installation.
Free of cost spectrum.

23. Every technologies have short comes
But its merits are the reason they are being used in various technologies
“Reveals a new world to be explored”.

24. References :-
An Introduction to Free-space Optical Communications Hennes HENNIGER1, Otakar WILFERT2,1 Institute of Communications and Navigation, German Aerospace Center (DLR), Wessling, Germany,2University of Technology Purkynova 118, CZ Brno, Czech Republic.
Free-Space Optical Communications at JPL/NASA H. Hemmati.
Integration Scenarios for Free Space Optics in Next Generation (4G) Wireless Networks Waqar Hameed*, S. Sheikh Muhammad** and Noor Muhammad Sheikh*.
Experimental Performance Study of a Very High Speed Free Space Optic Link at the University of Beira Interior Campus: a Case Study.
An Intra-Chip Free-Space Optical Interconnection, Jing Xue, Alok Garg, Berkehan Ciftcioglu, ShangWang, Jianyun Hu, Ioannis Savidis, yManish Jain,Michael Huang, Hui Wu, Eby G. Friedman, yGary W. Wicks, yDuncan Moore.
Google search-images.

25. Thank
you

26. Any Querries?