Transcript Free Space Opticsx

W H AT I F I T R A N S M I T
LIGHT WITHOUT
OPTICAL FIBRE?
Powerpoint Templates
\
‘Ofc’
v/s
‘fsO’
Incandescent light(~2800 K) max. attenuation.
Sunlight (~6000K)
Florescent lamp
oFree space loss(due to beam divergence) –impo.
oAtmospheric loss (not much in indoors)
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)
•Attenuation – Most Important
oAtmospheric 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)
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
Variations in Refractive Index along the
transmission path
Speckled pattern (both in time and space)
at the receiver
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.
•easy to encrypt any data travelling across
the FSO connection
•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).
•For communications between spacecraft, including
elements of a satellite constellation.
•As option for intra connectivity in companies.
1. An Introduction to Free-space Optical Communications Hennes HENNIGER1, Otakar
WILFERT2,1 Institute of Communications and Navigation, German Aerospace Center
(DLR), 82230 Wessling, Germany,2University of Technology Purkynova 118, CZ-61200
Brno, Czech Republic.
2 . w w w. w i k k i p e d i a . c o m
3 . w w w. f r e e s p a c e o p t i c s . c o m
4. Free-Space Optical Communications at JPL/NASA H. Hemmati.
5. Integration Scenarios for Free Space Optics in Next Generation (4G) Wireless Networks
Waqar Hameed*, S. Sheikh Muhammad** and Noor Muhammad Sheikh*.
6. Experimental Performance Study of a Very High Speed Free Space Optic Link at the
University of Beira Interior Campus: a Case Study.
7. 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.
8. Google search-images.