fibre optics

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.

THANK YOU