Fibre Optic Transmission
In this transmission technology, light waves are modified in intensity to transmit data. Digital pulses are converted to ON and OFF pulses of light which are used to transmit data. Fibre optic systems can only transmit digital data using this technique. Analog signals must be converted to digital signals before they can be transmitted over fibre optic facilities. A single fibre optic cable resembles a human hair. Lightwaves travel through the core of a fibre which is made up of very pure glass. The layer around the core is called cladding and is made up of less pure glass th~n the core.
The basic component of a fibre optic transmission system is the Transmitter. There are two primary devices that serve as lightwave sources. These are the Injection Laser Diode (ILD) and the Light Emitting Diode (LED). The fibre optic cable is the transmission medium. A photodetector or photodiode is used as the receiver which receives the lightwave pulses and converts them into electrical signals. Both types of devices emit and propagate light in a conical manner. However, they differ in the angle of emission and intensity.