Fiber Optics

BusyBrain.....Busy like a bee My Photos Learn Center Blog Favorite Links About us

History of Optical Communications

Interest in the use of light as a carrier for information grew in the 1960's with the advent of the laser as a source of coherent light. Initially the transmission distances were very short, but as manufacturing techniques for very pure glass arrived in 1970, it became feasible to use optical fibres as a practical transmission medium. At the same time developments in semi-conductor light sources and detectors meant that by 1980 worldwide installation of fibre optic communication systems had been achieved.

What are Optical Fibres?

Optical fibers are long, thin strands of very pure glass about the diameter of a human hair. They are arranged in bundles called optical cables and used to transmit signals over long distances. Optical Fibres are usually about 120 micrometres in diameter, which are used to carry signals in the form of pulses of light over distances up to 50 km without the need for repeaters. These signals may be coded voice communications or computer data

What are the parts of OFC?

If you look closely at a single optical fiber, you will see that it has the following parts:

· 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

Hundreds or thousands of these optical fibers are arranged in bundles in optical cables. The bundles are protected by the cable's outer covering, called a jacket.

Optical fibers come in two types:

· Single-mode fibers

· Multi-mode fibers

Single-mode fibers have small cores (about 3.5 x 10-4 inches or 9 microns in diameter) and transmit infrared light (wavelength = 1,300 to 1,550 nanometers).

Multi-mode fibers have larger cores (about 2.5 x 10-3 inches or 62.5 microns in diameter) and transmit infrared light (wavelength = 850 to 1,300 nm)

Some optical fibers can be made from plastic. These fibers have a large core (0.04 inches or 1 mm diameter) and transmit visible red light (wavelength = 650 nm) from LEDs.