A fibre optic cable is a type of telecom cable which is used for the transmission of data and voice traffic across long-distance with efficiency. There are also other types of telecom cables that are used for transmission of data and voice traffic, but they are all now mostly getting replaced by fibre optics cable.
What is the difference between fibre optic cable and other types of telecom cables?
In non-fibre cables, the communication is processed through electromagnetic waves, but in optical fibre, communication is conducted through light pulses which also increase the speed of transmission and reduce interference. The optical fibre cable types include single-mode optical fibre and multimode optical fibre.
One of the reasons for the replacement of other types of telecommunication cables, which includes telephone line cable, coaxial cable, Ethernet cable, in long-distance or outdoor deployments, is the mode of transmission.
Single-mode optical fibre
In a single-mode optical fibre, there is only one mode of light which can pass through cables, and the light wave passing through straight without any reflection or diffraction. The diameter of a core of the single-mode fibre is 8.3, and 10.5 micrometre and the cladding has the diameter of 125 micrometres. It has the capacity to carry a data rate of 10 gigabits over the distance of 80 km.
Multimode optical fibre
As the name suggests, multimode optical fibre has the ability to pass various modes of lights at a time, and it passes the light pulses in a refracted manner. There are two types of multimode optical fibre, step-index multimode and graded-index multimode.
Step index has large diameter with constant refractive index through which some rays that may be moved directly or straight while others are through zigzag and bounces by the core and propagate across the cable. As a result, they reach the receiver in different shapes which denotes the modes. Space must be left between the pulses to avoid overlapping. It is suitable for short-distance communication. The diameter of the step-index fibre is 105 to 125 micrometres. They provide up to 10GB maximum data rate for a few meters.
The graded-index has a core in which the refractive index decreases gradually when moving away from the centre of the core. So rays will follow snakelike movement because of the refractive index, which makes all the rays to travel at the same speed and reach the receiver at the almost same time. As a result, they also suffer from less dispersion. The diameters of graded-index multimode fibres are 50, 62.5 and 100 micrometres. The data rate of both Step index and Graded index multimode fibres are approximately the same (10GB for few meters), but there is less loss of rays due to dispersion in graded-index multimode fibres.