The basic introduction abut the optical fiber communication , the coding techniques used in optical communication (generation wise).

1. INTRODUCTION TO OPTICAL
FIBER COMMUNICATION
VIJENDRA KUMAR S. PRAJAPATI
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2. CONTENTS
• Introduction
• Literature Survey
• Types of coding technique
• Optical sources and detectors
• Need of coding
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3. INTRODUCTION
• Optical communication is broadly classified in
a. Wired communication b. Wireless communication
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Fig 1: Block diagram of optical wired communication

4. 4
Fig : Optical wireless communication

5. Optical wireless communication
Advantages
1.Low cost and ease of installation.
2.Data rate up to several GHz.
3.Use license free spectrum (780nm – 900nm and
1500nm – 1600 nm).
4.Less Multiple Interference.
Disadvantages
1.Limited Transmission Power.
2.High power consumption.
3.Sensitive to blocking and can’t pass through wall.
4.Beam dispersion is more.
5.Rain, snow, fog attenuation (10 - 100 dB/Km).
Optical wired communication
Advantages
1.Low loss of signal (0.2dB/Km).
2.Large data carrying capacity up to several THz.
3.High electrical resistance.
4.Prone to cross talk.
5.Low power consumption.
Disadvantages
1.High investment cost.
2.Splicing is very difficult.
3.Susceptible to physical Damage.
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6. LITERATURE SURVEY
FEC
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Block code Convolutional code Combination of both
1st Generation
(Early 1990’s)
2nd Generation
(post 1990’s)
3rd Generation
(early 2000’s)
Hamming code Orthogonal code RS code + Viterbi
Convolutional code
Reed – Solomon code
( RS )
BCH codes Block turbo code
Reed – Muller code
( RM )
Interleaving and
Iterative coding
LDPC code
( Approaches Shannon
limit)
Hard decision Hard decision Soft decision

7. CODING TECHNIQUE
Coding technique used in communication
Coding technique used in optical communication
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Source Coding Channel Coding Line Coding
Forward Error Correction Automatic Repeat Request
Error Correcting Codes Capacity Achieving Codes
Bose-Chaudhary-Hocquenghem
(BCH)
Reed- Solomon (RS)
Reed- Muller (RM)
Turbo Code
Low Density Parity Check
(LDPC)
Polar Codes

8. OPTICAL SOURCES
Optical sources
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Light Emitting Diodes
(LEDs)
Lasers
Semiconductor Laser Non-semiconductor Laser
Gain- guided
Index-guided
Quantum-well
Quantum-dot
Nd:YAG
Glass fibre
Planar
Dome
Surface emitter
Edge emitter
Super luminescent

9. OPTICAL DETECTOR
Optical Detector
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p-i-n photodiode Avalanche photodiode
Silicon p-i-n Germanium Heterojunction
Detection technique
Non-coherent Differentially
Coherent
Coherent

10. TRANSMISSION WINDOW
Band Wavelength Range Description
O- band 1260 nm – 1360 nm Original band
E- band 1360 nm – 1460 nm Extended band
S- band 1460 nm – 1530 nm Short wavelength band
C- band 1530 nm – 1565 nm Conventional band
L- band 1565 nm – 1625 nm Long wavelength band
U- band 1625 nm – 1675 nm Ultra long wavelength band
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• At 1550 nm the loss of any optical fibre is minimum i.e. 0.2
dB/Km. So 1550 nm is most widely used in optical
communication.
Table 1: Wavelength Range of the optical communication

11. SOURCES AND DETECTOR PAIRS
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• The most widely used Sources- Detector pair used in optical communication
is
Sources Detector wavelength
GaAlAs-GaAs Si 850 nm - 950 nm
InGaAsP-InP Ge / InGaAs-InP 1300 nm – 1550 nm
Impact of Various Coding Scheme on Optical Pulse Transmission in the Optical Channel

12. OPTICAL WINDOW
12Figure 2: Optical Window

13. NEED OF CODING
• Reducing the non-linear effect of optical channel.
• Improve the capacity of optical channel.
• Increase the speed of channel.
• Increase the spectral efficiency.
• Increases the data transmission Rate.
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