The document presents a technical seminar on laser communication systems, detailing their functioning, components such as transmitters and receivers, modulation techniques, and application areas. It highlights the advantages, including ease of deployment and immunity to electromagnetic interference, while also addressing limitations like atmospheric absorption and interference from background light. The conclusion emphasizes laser communication as a viable alternative to RF communications, particularly for high-performance inter-satellite links.

1. CAUVERY INSTITUTE OF TECHNOLOGY
MANDYA
VISVESVARAYA TECHNOLOGICAL UNIVERSITY
A Technical Seminar Presentation
On
“Laser Communication System”
Under the guidance of
Prof. Anitha H C
Associate professor
Presenting by:
NIKHIL N - 4CA20EC008
Department of Electronics & Communication
Engineering
2023-2024

2. Contents:
• Introduction
• How does Laser Communication Work?
• Laser transmitter and receiver
• Modulation
• Filters
• Application
• Advantages
• Disadvantages
• Conclusion
• Reference
Department of ECE, CIT Mandya 2

3. Introduction
• Laser communications systems are wireless connections through the
atmosphere.
• They work similarly to fiber optic links, except the beam is transmitted
through free space.
• While the transmitter and receiver must require line-of-sight conditions,
they have the benefit of eliminating the need for broadcast rights and
buried cables.
Department of ECE, CIT Mandya 3

4. Laser Transmitter and Receiver
Laser Transmitter Receiver
Optical fiber link
Direct Link
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5. Laser Transmitter:
• The Transmitter involves a signal processing
circuit, and a laser.
• A laser diode is used to create the laser signal.
• Laser Diodes include Photodiodes for feedback
to insure consistent output.
Department of ECE, CIT Mandya 5

6. Receiver
The receiver involves:
• Telescope(‘antenna’)
• Signal processor
• Detector
 PIN diodes
 Avalanche Photo Diodes(APD)
 Single or multiple detectors
Department of ECE, CIT Mandya 6

7. Modulation:
• AM
Easy with gas lasers, hard with diodes
• PWM (pulse width modulation)
Used by Ramsey in their kit
• PFM(pulsed Fm)
Potentially the highest bandwidth (>100khz)
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8. Filters:
• Sun shade over detector
• Shade in front of lens
• Detector spectral response
• Colored filters
• Absorb 50% of available light
• Difficult to find exact frequency
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9. Applications:
• Transmit voice for miles line-of-sight.
• Use weak signal modes for Cloud scatter.
• Transmit video with cheap pens.
• Transmit high speed data without WEP.
• Blind flies for easy extermination.
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10. Advantages:
• Ease of deployment
• Can be used to power devices
• License-free long-range operation (in contrast with radio communication)
• High bit rates
• Low bit error rates
• Immunity to electromagnetic interference
• Protocol transparency
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11. Disadvantages:
For terrestrial applications, the principal limiting factors are:
• Beam dispersion
• Atmospheric absorption
• Rain
• Fog (10 -100 dB/km attenuation)
• Snow
• Interference from background light sources (including the Sun)
Department of ECE, CIT Mandya 11

12. Conclusion:
• Laser communications offers a viable alternative to RF communications for inter
satellite links and other applications where high-performance links are a
necessity.
• High data rate, small antenna size, narrow beam divergence, and a narrow field
of view are characteristics of laser communications that offer a number of
potential advantages for system design.
Department of ECE, CIT Mandya 12

13. References:
1. Sadiku, M. N. O., Musa, S., & Nelatury, S. R. (2021). Free space
optical communications: an overview. European scientific journal,
ESJ, 12(9), 55.
2. Prof. Atul A. Padghan | prof. Ankit P. Jaiswal" study on laser
communication: features, application, advantages" published in
international journal of trend in scientific research and development
(ijtsrd), ISSN: 2456-6470, volume-2 | issue3, April 2019
3. (2020, December 23). Laser communication space.
Https://ivypanda.Com/essays/ laser-communication-links-in-space
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14. Thank You
Department of ECE, CIT Mandya 14