If you look closely at a single optical fibre, you will see that it has a thin glass centre of the fibre where the light travels, and outer optical material surrounding the core that reflects the light back into the core, and a plastic coating that protects the fibre from damage and moisture.
Optical fibres come in two types: Single-mode fibres and Multi-mode fibres. Single-mode fibres have small cores and transmit infrared laser light. Multi-mode fibres have larger cores and transmit infrared light from light-emitting diodes (LEDs). Some optical fibres can be made from plastic. These fibres have a large core and transmit visible red light from LEDs.
Compared to conventional metal wire (copper wire), optical fibres are:
- Less expensive – Several miles of optical cable can be made cheaper than equivalent lengths of copper wire.
- Thinner – Optical fibres can be drawn to smaller diameters than copper wire.
- Less signal degradation – The loss of signal in optical fibre is less than in copper wire.
- Low power – Because signals in optical fibres degrade less, lower-power transmitters can be used instead of the high-voltage electrical transmitters needed for copper wires.
- Digital signals – Optical fibres are ideally suited for carrying digital information, which is especially useful in computer networks.
- Non-flammable – Because no electricity is passed through optical fibres, there is no fire hazard.
- Lightweight – An optical cable weighs less than a comparable copper wire cable.
- Flexible – Because fibre optics are so flexible and can transmit and receive light, they are used in many flexible digital cameras including uses such as medical imaging, cars, space shuttles and in plumbing to inspect sewer lines.