FIBRE-OPTICS AND COMMUNICATIONS [Part-I]
With the technological advancement of the world towards progress and modernisation, there is a strong need of fast and uninterrupted communication. Thin hair-like optical fibres are continuously playing an extraordinary role in the growth of world-wide communication. They are spreading like neurons over the whole planet connecting people to communicate among each other within seconds irrespective of the distance between them and making life easier and faster.
WHY ARE OPTICAL FIBRES SO GOOD FOR COMMUNICATIONS?
Some of the advantages of optical fibres over conventional wires are as follows:
- Economic—Production of optical fibres is much cheaper as compared to conventional wires like that of copper wires.
- Corrosion free—Optical fibres do not conduct electricity due to which they are resistant to corrosive degradation and signals can be transferred even in harsh weather conditions like lightning storms.
- Higher information carrying capacity—The information carrying capacity of optical fibres is much greater than conventional wires because they transfer electromagnetic waves which having frequency of around two hundred trillion cycles per second. Moreover, they have very small diameter which is comparable with a hair strand because of which they can be bundled ina large amount than other wires and hence larger information can be transmitted.
- Less information loss—Since information is being transferred in the form of electromagnetic waves in an optical fibre because of which the loss of signal in optical fibre is less than in copper wire.
- Non-interference of signals—Light signals from one fibre do not interfere with those of other fibres in the same cable which is not possible in case of conventional wires. This allows clearer and uninterrupted communication.
PHENOMENON THAT MAKES OPTICAL FIBRES SO SPECIAL: TOTAL INTERNAL REFLECTION
Optical fibres operate on the phenomenon of Total internal reflection to transmit signals from the source to the receiver. The total internal reflection causes the light rays to reflect back after striking the boundary of the medium in an attempt to refract from optically denser medium to the optically rarer medium. The minimum angle of incidence which is required for complete bouncing back of light rays within the medium is known as critical angle.
COMPONENTS OF AN OPTICAL FIBRE
The important components of an optical fibre are:
- CORE—The innermost part of an optical fibre is known as core of the fibre. It is made up of glass combined with silica. All the electromagnetic signals enter the fibre via core. The refractive index of core is comparatively greater than clad which enhances the ability of signals to bounce back into the core after striking the boundary of the core-clad interface at an angle greater than critical angle.
- CLADDING—The core of the optical fibre is surrounded by another layer made up of combination of glass and silica. It has refractive index slightly lower than the core. Light rays travelling through the fibre core reflect off this core-cladding interface when they travel through the fibre by total reflection.
- BUFFER JACKET—The outer covering of clad is known as buffer jacket. It is usually made up of plastic. It acts as a protective covering of core and clad.
- OUTER JACKET—The outer jacket surrounds the cable to protect the fibre against scratch, solvents, and other pollutants.