Fibre Optic Cable

A fibre optic cable is made of glass or plastic and transmits signals in the form of light. Optical fibre use reflection to guide light through a channel. A glass or plastic core is surrounded by a cladding of less dense glass or plastic. The difference in density of the two materials must be such that a beam of light moving through the core is reflected off the cladding instead of being refracted into it.

Following are two major types of fibre optic cable:

• Single Mode: Uses a specific light wavelength. The cable's core diameter is 8 to 10 micrometre. Single mode fibre is often used for intercity telephone trunks and video applications.
• Multi Mode: Uses a large number of frequencies. The cable core is larger than that of single mode fibre. Multimode fibre is the type usually specified for LAN's and WAN's.

Advantages:

1. Lower cost in the long run.
2. Low loss of signal.
3. Large data carrying capacity.
4. No crosstalk between cables.
5. Immunity to electrical noise.
6. Reduced size and weight cables.

Disadvantages:

1. High investment cost.
2. Need for most expensive optical transmitters and receivers.
3. Unidirectional light propagation.
4.  More expensive to repair/maintain.