Fibre and its capacity
Fibre conductors have an almost unlimited capacity to transmit. However, a limitation arises from the electronics on the transmitter and the receiver ends. Transmitter and receiver equipment convert electrical signals into light signals and vice versa.
What is fibre?
Optical fibre is a very thin strand of glass that transmits light. The light that is directed in at one end flows intact out of the other end without escaping along the way. Today, the substance that is most commonly embedded at the core of the fibre optic is Germania Silica (pure glass), which is encased in a sheath. Fibre technology is built on developing the core to have a higher refractive index than its surrounding sheath. This then enables the light that passes through to be continuously refracted from the sheath back to the core. In this way, the light is prevented from escaping as it travels along the optical fibre.
- One fibre optic strand, comprising of core and sheath has a diameter of 125 microns, of which the core occupies about 10 microns.
- The strands are wrapped in different layers of plastic
- A fibre cable contains from 2 up to 1000 fibre optic strands
- The light that is most commonly used is infrared light in the range of 1550 nm wavelength. The attenuation of such a fibre is about 0.2 dB / km, which creates a transmission distance of between 100 and 150 km without amplifiers.
- In order to transmit information, the light is encoded in digital light pulses generated by a laser (or LED) at the transmitting end.