fibre optics
DESCRIPTION
Pakistan Zindabad.....TRANSCRIPT
Fiber optics The Turning Point
Presented by:Syed Safdar Abbas
03F-EE-20 Mohd. Shehzad Nazir
03F-EE-71
HISTORICAL BACKGROUND
John Tyndall experiment -1870
John Logie experiment-1950 Charles Kao and George Hockham
proposal - 1966 First fiber optic television
transmission -1980
What are Fiber Optics ?
Long, thin strands of very pure glass about the diameter of a human hair.
Arranged in bundles called optical cables and used to transmit light signals over long distances
COMPONENTS
Core - Thin glass center of the fiber where the light travels
Cladding - Outer optical material surrounding the core that reflects the light back into the core
Buffer coating - Plastic coating that protects the fiber from damage and moisture
How Does an Optical Fiber Transmit Light?
Total internal reflection - The light in a fiber-optic cable travels through the core by constantly bouncing from the cladding.Light waves can travel a greater distance
Degrading - Light signal degrades within the fiber, mostly due to impurities in the glass.
Extend of degradation - 850 nm = 60 to 75 percent/km; 1,300 nm = 50 to 60 percent/km; 1,550 nm is greater than 50 percent/km). Some premium optical fibers show much less signal degradation -- less than 10 percent/km at 1,550 nm.
FACTORS AFFECT THE PROPAGATION OF
LIGHT Coherence of the light source. The size of the fiber. The composition of the fiber. The numerical aperture of the
source and the fiber. The amount of light injected into
the fiber.
CLASSIFICATION
Single-mode fibers
1. Light follows a single path.
2. Exceedingly small cores about
3.5 x 10-4 inches or 9 microns in diameter.
3. Light thus travels parallel to the axis,creating little pulse dispersion.
4. Commonly use in telecommunication and cable system.
SINGLE MODE FIBER
Multimode cable - Made of glass fibers, with a common diameters in the 50-to-100 micron range for the light carry component (the most common size is 62.5).
CLASSIFICATION OF MULTIMODE CABLES
STEP-INDEX MULTIMODE FIBER 1. a large core, up to 100 microns in
diameter.
2. Zigzag path.
3. These alternative pathways cause the different groupings of light rays, referred to as modes
STEP-INDEX MULTIMODE FIBER
GRADED-INDEX MULTIMODE FIBER
1. A core in which the refractive index diminishes gradually from the center axis out toward the cladding
2. The higher refractive index at the center makes the light rays moving down the axis advance more slowly than those near the cladding.
GRADED-INDEX MULTIMODE FIBER
Advantages of Fiber Optics
Less expensive Thinner Higher carrying capacity Less signal degradation Light signals Digital Signals Non-flammable
WHY FIBER OPTICS REPLACES COPPER?
SPEED: Fiber optic networks operate at high speeds - up into the gigabits
BANDWIDTH: large carrying capacity
DISTANCE: Signals can be
transmitted further without needing to be "refreshed" or strengthened
RESISTANCE: Greater resistance to electromagnetic noise such as radios, motors or other nearby cables.
MAINTENANCE: Fiber optic cables costs much less to maintain
CONCLUSION
Fiber Optics are replacing copper wire.
Fiber Optics providing the backbone for many network systems.
Now a days in Pakistan it is widely used in telecommunication and computer networks.
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