Fibre optics

The process of using fibre optics is based on the use of light to communicate. There are two types of fibres: single mode and multi-mode. Single-mode fibres are characterized by a narrow core with a constant refractive index. Gigabit-speed data is possible with single-mode fibres. Single-mode patch cords are typically yellow and have a relatively low pulse-dispersion index.

Plastic Optical Fibre is easier to install and terminate than glass or copper wire systems. The outer sheath is made from a rugged plastic, and it may contain an additional inner tube that is reinforced with Kevlar for added strength. Each fibre has multiple single-core fibres, and the cladding is 125 microns thick. Single-mode fibres measure eight microns in diameter. Fibre-optic cables are primarily used in industrial settings, but some television services and university campuses also use them. New telecoms providers such as Telkom are installing large networks using blown-fibre deployment.

Optical fibres are also widely used as sensors. Because they carry light, they are free from interference and are safe to use in hazardous or explosive environments. Optical fibre sensors fall into two general categories. These sensors use a change in the propagation of light through a fibre to detect a particular quantity. For example, a change in propagation velocity allows the measurement of temperature. Most optical fibre measurements use differential measurement techniques. This means that one optical fibre is subject to the influence of the measurand, while the other serves as the reference.

Fiber enables the next generation of applications that rely on high-throughput, low-latency, and high-reliability connections. The speed and range of fiber-optic cables may be increased by two or three times or more in the future. In the meantime, the cost of such connections continues to grow as a result of more efficient research. The benefits of fiber are undeniable. The use of optical cables for communications services is growing rapidly.

In the 1840s, Swiss physicist Daniel Colladon discovered a light pipe. This water pipe carried light by internal reflection. In 1870, Irish physicist John Tyndall demonstrated this effect at the Royal Society. Tyndall shone light into a jug filled with water, and the light curved around, following the path of the water. This principle is the same as the process of bending light in fibre optics. Attempts to use fibre optics as a gastroscope, for example, were made in the 1920s by Germans Heinrich Lamm and Walter Gerlach.

Micro-bends and sudden temperature changes cause the transmitted light pulses to reflect back at its original position. This is called Brillouin scattering. It is similar to Raman scattering, except that the reflected light pulses are generated by a localized change in temperature. In either case, the changes in temperature cause localized scattering of the transmitted laser beam. It can cause a tripped-up signal if it is connected to a power pipeline.