Optical communication introduction

3. Out Line
• Introduction to optical fiber communication
• Ray Optics
• Principle of Optical Communication
• Structure of Optical fiber
• Classification of optical fibers
• Optical Communication Block
• Advantages
• Disadvantages
• Applications
• References

4. • Optical communication, is communication at a distance
using light to carry information.
• It can be performed visually or by using electronic devices.
• Optical Communication is the most modern mode of wired
communication.
• Optical communication is also the youngest mode of communication.
However its capabilities supersede all other modes of communication.
• Before optical communication the most of the communication was in
radio and microwave domain which has frequency range orders of
magnitude lower than the optical for the electromagnetic spectrum.

5. Ray Optics: basic laws
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6. Snell's Law

7. Refractive index
Refractive index of a medium is represented by n.
It is defined as ration of velocity of light in free space to velocity of light in the given medium.
I.e. 𝒏 =
𝑪
𝑽
*The index varies with a number of parameters, such as wavelength and temperature.
Air 1.0
Water 1.33
Magnesium fluoride 1.38
Fused silica (SiO2) 1.46
Sapphire (Al2O3) 1.8
Lithium niobate (LiNbO3) 2.25
Indium phosphide (InP) 3.21
Gallium arsenide (GaAs) 3.35
Silicon (Si) 3.48
Germanium (Ge) 4.0
Refractive indices of some materials
Rarer Medium: A medium in which refractive index is less
Dancer Medium: A medium in which refractive index is high.

8. Rarer medium
Dancer medium
Ray Optics
Normal
Interface

9. Rarer medium - 𝑛2
Dancer medium - 𝑛1

10. Critical angle

11. Rarer medium - 𝑛2
Dancer medium - 𝑛1
Total- total energy
Internal – same medium
Reflection (TIR)
Principle of Optical communication – Total Internal Reflection

12. Total internal reflection

13. Structure of Optical fiber Structure of Optical fiber cable
Core- A medium which has high refractive index (𝑛1)
Cladding- A medium which has low refractive index (𝑛2)
Buffer coating - Used for mechanical protection

14. Core
Cladding
Cladding
Core
Refractive Index Profile
Core
Cladding
Cladding
Core
Refractive Index Profile Output Pulse
Input Pulse
Core
Cladding
Cladding
Core
Refractive Index Profile Output Pulse
Input Pulse
Classification of Optical Fibers

15. Optical Fiber Communication Block Diagram

16. Fiber Optic Data Transmission Systems
•Fiber optic data transmission systems send information
over fiber by turning electronic signals into light.
• Light refers to more than the portion of the
electromagnetic spectrum that is near to what is visible
to the human eye.
• The electromagnetic spectrum is composed of visible
and near-infrared light like that transmitted by fiber, and
all other wavelengths used to transmit signals such as
AM and FM radio and television.

17. Advantages
• Low Attenuation
• Very High Bandwidth (THz)
• Small Size and Low Weight
• No Electromagnetic Interference
• Low Security Risk
• High speed
• Distance of transmission
• Cheap
• Long life span

18. Limitations
• Transmission over fiber is limited by
• Attenuation,
• Distortion
• Scattering and
• Dispersion.
• Multimode fibers may experience
Multimode dispersion: The delayed rays cause pulse spreading
Chromatic dispersion: Individual wavelengths may travel at
different speeds.
• Dispersion creates an inherent operational limit defined as a bandwidth-
distance product (BDP).
• Difficult to splice.

19. Applications
• The application and uses of optical fiber can be seen in:
• Medical Industry – Surgery and Dentistry
• Communication
• Defense
• Industries
• Broadcasting
• Lighting and Decorations
• Military and Aerospace
• Computer networks
• Mechanical Inspection
• TV cables
• Internet
• Remote Sensing

20. References
[1] M. Artiglia, “Mode field Diameter measurements in single-mode optical fibers,” J. Light
wave Tech. Vol. 7, no. 8, pp. 11391152, 1989.
[2] J. A. Buck, “Fundamentals of Optical fibers,” John Wiley & Sons, 1995.
[3] J. Sakai, and T. Kimura, “Bending loss of propagation modes in arbitrary-index profile optical
fibers”, Applied Optics vol. 17, no. 10, pp 1499-1506, May 1978
[4] A. W. Snyder and J. D. Love, "Optical Waveguide Theory," Chapman and Hall, 1983.
[5] K. Petermann, “Microbending loss in mono mode fibers,” Electron. Lett., vol. 20, no. 3, pp.
107- 109, 1976.
[6] S. E. Miller and I. P. Kaminow, Eds., “Optical Fiber Telecommunications II,” Academic Press,
1988.
[7] J. Sakai and T. Kimura, “Birefringence and Polarization Characteristics of Single-Mode optical
Fibers under Elastic Deformations”, IEEE Journal of Quantum Electronics, vol. QE-17, no. 6,
[8] C. D. Poole, N. S. Bergano, R. E. Wagner, and H. J. Schulte, “Polarization Dispersion and
Principal States in a 147-km Undersea Lightwave Cable”, Journal of Light wave Technology,
vol. LT-6, no. 7, pp 1185-1190, July 1988. pp 1041-1051, June 1981.
[9] D. Marcuse, “Theory of Dielectrical Optical Waveguides, Second Ed.,” Academic Press, 1991.