Ofc introduction
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Optical fiber communication involves transmitting information through pulses of light through optical fibers. Optical fibers are composed of thin glass threads that guide light waves with minimal attenuation using the principle of total internal reflection. Information is encoded as electrical signals, converted to light signals, transmitted through the fiber, and converted back to electrical signals. Key advantages of optical fibers include being non-conductive, having high bandwidth, low loss, and electromagnetic immunity. Optical fibers have applications in long-distance networks, telephone lines, premises networks, undersea cables, and areas with high EMI or lightning risk.
Ofc introduction
- 2. Optical Fiber Communication • Optical Fiber Communication – Method of transmitting information by sending pulses of light through an optical fiber.
- 3. OPTICAL FIBER Main job of optical fiber is to guide light waves with a minimum attenuation. Optical fibers are composed of fine threads of glass in layers. The fine threads are of silica glass mix with some dopant material. It transmits the Optical waves (Light) through it at the speed of 2/3 of speed of light in vacuum observing the total internal reflection principle.
- 5. Transmission sequence • Information is encoded into electrical signals. • Electrical signals are converted into light signals. • Light travels down the fiber. • A detector changes the light signals into electrical signals. • Electrical signals are decoded into information
- 6. Advantages of Fibre Optics • Optical Fibers are non conductive (Dielectrics) • Electromagnetic Immunity • Large Bandwidth • Low Loss • Small, Light weight cables • Available in Long lengths • Security
- 7. Application of fiber optics in communications • Common carrier nationwide networks. • Telephone Inter-office Trunk lines. • Customer premise communication networks. • Undersea cables. • High EMI areas (Power lines, Rails, Roads). • Control systems • High lightning areas • Military applications
- 8. Normal reflection, refraction and total internal reflection n2 n1 n2 n1 n2 n1 N N N θ2 θ2 = 90 R.Ray Totally internally reflected rayθ1 θr I.Ray Fresnel Refl. θ1 θ1 = θr θ1 = θc when θ2 = 900 (C.A) θ1 = θc n1 > n2 • Snell’s Law:- n1 sin θ1 = n2 sin θ2
- 10. Light propogation in optical fibers • Follows Laws of Reflection and Refraction. • Different Wavelengths of Light travel at different speeds in the same material. • Refractive index of any Fiber material, n= c/v where c is the Velocity of light in free space and v is its velocity in a specific material.
- 11. The Optical Fibre structure Claddi ng 125 µm Core 8-100 µm For BSNL Internal Circulation only
- 12. Fiber Types Multimode Multimode Single Mode
- 13. Fiber Types
- 14. Optical fiber wavelength • Optical fiber transmission uses wavelengths which are above the visible light spectrum, and thus undetectable to the unaided eye.
- 15. Optical window •There are ranges of wavelengths at which the fiber operates best. Each range is known as an operating window. • Each window is centered around the typical operational wavelength
- 16. Window • A window is defined as the range of wavelengths at which a fibre best operates. Window Operational Wavelength 800nm - 900nm 850nm 1250nm - 1350nm 1300nm 1500nm - 1600nm 1550nm
- 18. Attenuation • Loss in optical power while light is traveling along the fiber is termed as attenuation • Attenuation varies with wavelength of light • Attenuation is directly proportional to the length of the cable.
- 19. Attenuation
- 20. Radiation due to macro bending
- 21. Radiation due to micro bending
- 22. NUMERICALAPERTURE • Numerical aperture is defined as the “light gathering” capacity of the fiber. • Only light injected into the fiber at angles greater than critical angle will be propagated
- 23. Numerical aperture Acceptance cone Eventually lost by radiation Propagated by the fiber
- 24. Dispersion • Dispersion is defined as the signal broadening or spreading while it propagates inside the fiber (spreading of light in time/pulse spreading).
- 25. Dispersion
- 26. • Every laser source has a range of optical wavelengths; figure shows examples for LD and LED laser sources.
- 27. How to reduce material dispersion? • By using sources with smaller band width or spectral width LED 20-100 nm LD(semiconductor) 1-5 nm YAG laser 0.1 nm He Ne laser 0.002nm
- 28. Wave guide dispersion • Predominant in SM Fibers • Occurs because guided optical energy is divided between core and cladding • On account of energy traveling at slightly different velocities between core and cladding.
- 29. Waveguide Dispersion • Whenever any optical signal is passed through the optical fiber, practically 80% of optical power is confined to core & rest 20% optical power into cladding.
- 30. BANDWIDTH • It is defined as the amount of information that a system can carry such that each pulse is distinguishable by the receiver.
- 32. OFCable The main Parts of OF Cable are Optical Fibre Buffer Strength member Jacket
- 33. Parts of Loose Tube Fiber
- 34. Aerial Cable
- 35. Armoured Cable