Fibre Optics Transmission System (FOTS) is a part of the fibre optics technology. This is a transmission system in the communications industry in which light is transmitted through thin glass fibres. Information is sent by 'modulating' the light that is transmitted. Light-sensitive semi-conductor devices detect these signals. The signals, in turn, are generated again so as to transmit the information. The signals are demodulated in order to retrieve the information.

In Fiber Optics Transmission Systems, transmission of data is accomplished using electromagnetic energy in the form of light waves. The FOTS is basically Electro-Opto-Electronic (EOE) and these systems are generally referred to as 'photonic'. They are EOE in nature because the signal originates and terminates in electrically based systems only. Most of these systems are digital, though a few of them are also analog.

Optical fibres are extensively used in fibre optic communication, which enables transmission of digital data over longer distances and at data rates higher than most of the other forms such as wired and wireless communications. Besides transmitting data at incredible speeds, these communications systems also greatly reduce the cost of transmission.

Connected by a fibre optic cable, FOTS consists of a fiber optic transmitter and receiver. These systems offer several benefits over the traditional copper wire or coaxial cable systems. These systems can carry tremendous amount of information and transmit it at a much faster speed when compared to copper wire or coaxial cable. This factor makes these systems an ideal alternative for 'serial digital data' transfer. A major advantage is that fibre does not conduct electricity and is not affected by interferences such as lightning.

Since the fibre is made of glass, there will not be any possibility of corrosion and most of the chemicals cannot affect the cable, because of which the cable can be buried in any type of soil. Since monitoring the cable is relatively simple but extremely difficult to tap, these fibres form excellent alternative for use in secure communications systems. Fibre optics is fast becoming an important technology for telecommunications companies aspiring to expand their networks.