Free Space Optics Technology

1. BY:
Mujeeb ur Rehman, B.E-VII
Electrcial Engineering Department, SUKKUR IBA
Mujeeb.soomro@iba-suk.edu.pk

2.  IntroductionIntroduction
 HistoryHistory
 Why Free Space Optics?Why Free Space Optics?
 How FSO works?How FSO works?
 ChallengesChallenges
 SafetySafety
 Applications of Free Space OpticsApplications of Free Space Optics

3. What is Free-Space Optics (FSO)?
• FSO is a wireless technology that transmits data via
laser beams.
 FSO uses light to transmit data between buildings that
have clear a line of sight (LOS).

4. FSO TRANSMITTER FSO RECIEVER

5. 1. Originally developed by the
U.S military and NASA.
2. The invention of lasers in the 1960s
revolutionized free space optics.
3. In 1880 Alexander Graham Bell
created the photophone .

6. FSO can send large amounts of data (around 2.5 Gbps of
data).
Can transmit at distances around 4 km (almost 2 and one
half miles).
No need to get a license, the spectrum used is an unlicensed
worldwide.
The cost is often less than that of using fiber optic cables.
FSO systems can be installed quickly (in days).
because it uses light there is no RF interference.

7. With FSO, especially throughWith FSO, especially through
the window, no permits, nothe window, no permits, no
digging, no feesdigging, no fees

8. 1 Network traffic
converted into
pulses of invisible
light representing
1’s and 0’s
2 Transmitter projects the
carefully aimed light pulses
into the air
5 Reverse direction data
transported the same way.
• Full duplex
3 A receiver at the other end of the
link collects the light using lenses
and/or mirrors
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

9. FSO systems use optical wireless link each having:
a transceiver with a laser or LED transmitter
a lens or telescope (can have more that one)
shaping overcomes building movement
a receiver usually a semiconductor (photodiode)
May also employ servo motors, and mirrors.
FSO operates in the infrared (IR) range around 850 and
1550 nm (frequencies around 200 THz).

10. Rapid installations without
trenching and permitting.
Direct connection to the end
user.
Bypasses the building owner.

11.  License-free operation
 High bit rates
 Low bit error rates
 Immunity to electromagnetic interference
 Full duplex operation
 Very secure due to the high directionality and narrowness of the beams
RONJA , a free implemantation of FSO utilizing
High intensity LEDs

12. Sunlight
Alignment
Fog
Each of these factors can “attenuate” (reduce) the signal.
However, there are ways to mitigate each environmental factor.
Scintillation
Range
Obstructions
Low Clouds

13. Absorption or scattering of optical
signals due to airborne particles
High availability deployments
require short links that can operate
in the fog.

14.  Low Clouds
 Very similar to fog
 Rain
 Extremely heavy rain (can’t see through
it) can take a link down
 Heavy Snow
 May cause ice build-up on windows
 Sand Storms
 Likely only in desert areas; rare in the
urban core

15. Beam spreading and wandering due to propagation through air pockets of
varying temperature.
This atmospheric turbulence can deteriorate the quality of
the image formed at the receiver, and can cause fluctuations in
both the intensity and the phase of the received signal .
These intensity fluctuations, often referred to as scintillation
Solution: Large receiver diameter to cope with image dancing
Challenges:
Scintillation

16. The two major concerns involve eye exposure to light
beams and high voltages within the light systems and their
power supplies.
Strict international standards have been set for safety and
performance.
Choice of the wavelength 1550 nm yields better eye
safety than for the common 850 nm for FSO
wavelength

17. APPLICATIONS OF FSO
1.MILITARY AND GOVERNMENT
 Secure and undetectable FSO system can connect large
areas safely with minimal planning and deployment time.

18. 2. Wireless Service Provider
 Unlike microwave or fiber, deployment of FSO does not
require spectrum licensing, physical disruption to a
location, or government zoning approvals. Carriers are
free to grow their business.

19. 3. Enterprise connectivity
 To cross a public road or other barriers which the
sender and receiver do not own.
 Companies, airports, hospitals and schools can use
safe, secure Free space optical wireless links to
connect buildings within their campus environments.

20. 4.Temporary network installation (for events or other
purposes)
5.Reestablish high-speed connection quickly (disaster
recovery).

21. 6.FSO on High-Altitude Platforms (Future
Application)
•HAPs are aircraft or airships situated well above the clouds
at typical heights of 17 to 25 km.
•Where the atmospheric impact on a laser beam is less severe than
directly above ground
•1.25 Gbps for Downlink
•10 Gbps for Upwnlink