A cable that is used to transmit the data through fibres (threads) or plastic (glass) is known as an optical fibre cable. This cable includes a pack of glass threads that transmits modulated messages over light waves.
Principle:
Optical Fibre works on the principle of Total Internal Reflection.
Total Internal Reflection:
When the light ray travels from denser medium to rarer medium the refracted ray bends away from the normal. When the angle of incidence is greater than the critical angle, the refracted ray again reflects into the same medium. This phenomenon is called total internal reflection.
Characteristics of Optical fibre
- It has a large bandwidth.
- The optical frequency of 2 x 1014 Hz can be used and hence the system has higher bandwidth.
- Thus optical fibres have greater information-carrying capacity due to greater bandwidth.
- In an optical fibre system transmission losses are as low as 0.1 db/km.
- Optical fibre is of small size and lightweight as compared to electrical fibre.
- Optical fibre communication is free from electromagnetic interference.
- Optical fibre does not carry high voltage and current hence they are safer than electrical cable.
- Optical Fibres are flexible and have high tensile strength. Thus can be bent or twisted easily.
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