2. What is LASER Communication??
Laser communication systems
are wireless connections through
the atmosphere.
They work similarly to fiber
optic links, except the fact that,
in lasers, beam is transmitted
through free space.
3. LASER Communication System
Basic block diagram of laser communication system
MODULATOR
LASER DIODE PHOTON SENSOR
DEMODULATOR
LASER BEAM
DATA TO BE SENT DATA RECOVERED
Transmitter Side Medium Receiver Side
5. The LASER Diode is being turned
ON/OFF quickly as needed according to the
OOK/PWM/PFM signal.
Modulation Techniques:
ON-OFF Keying(OOK)
Pulse Width
Modulation(PWM)
Pulsed Frequency
Modulation(PFM)
OOK
PWM
PFM
6. RECEIVER
Receiver consist of
Telescope (referred as Antenna)
It concentrates large number of photon into a smaller area
Photon sensor
(a) Photon Multiplier Tubes
(b) Avalanche Photodiode
Signal processing unit
8. Why not Fiber Optics??
Installation cost
Maintenance cost
Cannot be used in Satellite links
Laser Communication is low cost and can be
applicable where Fiber Optics is impractical to use.
9. Why not Microwave??
Beam width: Laser beam
width is narrower than that of
Microwave antennas.
Bandwidth: very much larger
for Laser than microwave.
Security: Laser is more secure
than microwave.
Power: Low power needed
for laser compared to microwave.
Very antenna size for Laser
as compared to microwave.
10. Disadvantages!!
Laser link can be affected by-
Atmospheric absorption
Fog, Rain, Pollution (smoke)
Physical obstructions
Solar radiations
These can be reduced by using Laser tuning,
multiple number of transmitters, filters etc.
11. Current Applications
Defense and sensitive areas
At airports for communication across the runways
Mass communication
NASA
Satellite – satellite communication
Earth – satellite communication
12. Future Scope
It is more secure and provides high bandwidth
requirements. The low power consumption is also a
great advantage.
It can be the mostly used technique worldwide in
near future.