Laser communication systems use lasers to transmit data through free space instead of fiber optic links. The basic components are a transmitter with a laser diode, modulator and signal processing unit, a receiver with a telescope, photon sensor and signal processing unit, and the laser beam that travels through the medium. Common modulation techniques are ON-OFF keying, pulse width modulation and pulsed frequency modulation. Laser communication offers advantages over fiber optics and microwaves by having lower installation and maintenance costs, the ability to transmit through free space including satellite links, higher bandwidth, more secure and narrow beams compared to microwaves. While atmospheric effects can impact the laser link, techniques like tuning and multiple transmitters can reduce these impacts. Current applications

1. LASER COMMUNICATION
Arijit Baishnab
U.I.T. Burdwan University
Roll No. 20122033
Reg. No. 2564 of 2012-13

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

4. Transmitter
Transmitters consist of
 Signal Processing unit
 Laser Diodes

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

7. Why LASER Communication??
Current mostly used high speed technologies:
 Fiber optics
 Microwave

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.