optical fiber communications
DESCRIPTION
OPTICAL FIBER COMMUNICATIONS. Optical Fibres. Strength Member. Sheath 1. Aluminum Tape. Sheath 3. Sheath 2. Steal Wire Reinforcement. INFORMATION SUPER HIGHWAY. Introduction. Optical Fiber It is a glass filament or wire which carries light. - PowerPoint PPT PresentationTRANSCRIPT
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OPTICAL FIBER COMMUNICATIONS
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Optical Fibres
Sheath 1
Sheath 2Sheath 3
Aluminum Tape
Strength Member
Steal Wire Reinforcement
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IntroductionOptical Fiber It is a glass filament or wire which carries
light. It is a cylindrical waveguide that operate at
optical frequency. It confines electromagnetic energy in the form
of light.
●COMMUNICATION It may be broadly defined as the transfer of
information from one point to another.
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Light is the form of electromagnetic Wave just as radio waves, but with high frequency and shorter wavelength.
Spectrum Frequency Wavelength
Radio waves 100 KHZ to1 THZ 3KM to 300 µm
Infra Red light 1 THZ to 100 THZ 300 to 3 µm
Optical Communication
176 THz to 375 THZ
1.7 to 0.8 µm
1550 nm Window 193.5 THz 1.550 µm
1310 nm Window 230 THz 1.310 µm
850 nm Window 353 THz 0.85 µm
Visible Light 428 to 750 THZ 0.7 TO 0.4 µm
UV,X & γ rays 750 to 10 7 THZ 0.4 to 3x10 - 6 µm
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0 102 104 106 108 1010 1012 1014 1016 1018 1020 1022
Long wave
Standard
broadcast VHF
UHFShort wave
Radiofrequencies
Microwave
Millimeter
Wave
Far infrared
infrared
Ultraviolet
X-Rays
Gamma Rays
Cosmic rays
Red
~0.7 µm
Violet
~0.4 µm
1.7 µm 0.8 µm
Optical Fibre Communication
Frequency (Hz)
Wavelength3000 km 30 km 300 m 3 m 3 cm 0.3 mm 3 µm 30 nm 0.3 nm 3 pm 0.3 pm
f = 1/T λ = c/f c = 3x108 m/s
f = 100 Hz λ = 3x108 m f = 1 GHz λ = 0.3 m
f = 100 KHz λ = 3x103 m f = 1 THz λ = 300 µm
f = 100 MHz λ = 3 m f = 200 THz λ = 1.5 µm
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HISTORYHollow Logs, Drum (different sizes), Wind Instruments
(pipes), Smoke Signals, Signal fires and Signaling lamps.
The first optical fiber exhibited very high attenuation i.e. 1000 dB/Km. While coaxial cable losses were 5-10 dB/Km.
Fiber losses were reduced to below 5 dB/Km.Development of fiber waveguides with optical
frequencies at small wavelengths requires the development of all optical components.
Laser Life at the start was 1000 Hrs & now is 100 years.
At present two optical windows are in operation i.e. 1310 nm ,1550nm.
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Advantages of Optical FiberEnormous potential bandwidth The maximum capacity of single mode step index fiber is
1.6 Tb/Sec w.r.t coaxial cable bandwidth of 500 MHZ.Small size and weight
Optical fibers have very small diameter i.e. 125um which is just like a human hair while the dia of one copper is 0.8mm.The ratio of weight as compared to other cables is 25:1.
Electrical isolationOptical fibers are fabricated from glass which are electrical insulated hence they don't exhibit interference problem.
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Advantages of Optical FiberImmunity to Interference & Cross talk
The material of optical fiber is dielectric/glass hence there is no possibility of cross talk or leakage.
Signal SecurityThe light from optical fibers doesn't radiate significantly and therefore they provide a high degree of signal security.
Low transmission lossLaser light travels with high speed on pure transparent glass. This development of optical fiber over the last twenty years has resulted in the production of O/F cables with very low attenuation i.e. 0.2 dB/Km.
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Advantages of Optical FiberRuggedness & Flexibility
Cable structures have been developed which have proved flexible, compact & extremely high.
System Reliability & Ease of MtceDue to low transmission loss, intermediate repeaters & line amplifiers are reduced. Hence with few repeaters system reliability is generally enhanced. The optical component life time is 20 to 30 years.
Potential Low CostThe glass which generally provides the optical fiber transmission medium is made from sand which is available in abundance.
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Disadvantages of Optical FiberVery small hole on the surface of fiber may
weakens the tensile strength.A small bend on optical fiber causes radiation loss.Alignment problem, connectors & core
misalignment.The cost of fusion splicing is high.The fault localization is some what difficult.Clean environment is required during splicing. A
small dust particle can create high attenuation.