Solution:

The basic components of an optical communication system are shown in Figure, above.

A serial bit stream in electrical form is presented to a modulator, which encodes the data appropriately for fiber transmission.

A light source (laser or Light Emitting Diode - LED) is driven by the modulator and the light is focused into the fiber.

The light travels down the fiber (during which time it may experience dispersion and loss of strength). At the receiver end, the light is fed to a detector and converted to an electrical form.

The signal is then amplified and fed to another detector, which isolates the individual state changes and their timing.

It then decodes the sequence of state changes and reconstructs the original bit stream.

The timed bit stream so received may then be fed to a user device.

Optical communication has many well-known advantages:

Weight and Size:

• Fibre cable is significantly smaller and lighter than electrical cables to do the same job. In a wide-area environment, a large coaxial cable system can easily involve a cable of several inches in diameter and weighing many pounds per foot.

Material Cost:

• Fibre cable costs significantly less than copper cable for the same transmission capacity.

No Electromagnetic Interference:

• Because the connection is not electrical, you can neither pick up nor create electrical interference (the major source of noise). There are very few sources of things that can distort or interfere with the signal.

Better Security:

• It is possible to tap fiber optical cable. But it is very difficult to do and the additional loss caused by the tap is relatively easy to detect. There is an interruption to service while the tap is inserted and this can alert operational staff to the situation.

Open-Ended Capacity:

• The maximum theoretical capacity of installed fibre is very great (almost infinite). This means that additional capacity can be had on existing fibres as new technology becomes available.