Nowadays when come to a network infrastructure, fiber cable are always the first option. With a fiber optic data network, your telecommunication infrastructure is easily scalable with the maximum security, reliability, and most cost-effective solution, truly meet today's connectivity and highest bandwidth demands.

Fiber optic cable is able to function as a data transfer medium through the transmission of light because the hollow, round glass or plastic wires reflect the light back to the core of the wire, causing the cable to act as a waveguide. Glass and plastic offer widely different characteristics and used in very different applications.

Although fiber optic cables offer a far superior performance to that which can be achieved with other forms of cable, they nevertheless suffer from some levels of attenuation. This is caused by several effects:

Loss associated with the impurities There will always be some level of impurity in the core of the optical fiber. This will cause some absorption of the light within the fiber.
Loss associated with the cladding When light reflects off the interface between the cladding and the core, the light will actually travel into the core a small distance before being reflected back. This process causes a small but significant level of loss and is one of the main contributors to the overall attenuation of a signal along a fiber optic cable.
Loss associated with the wavelength It is found that the level of signal attenuation in the optical fiber depends the wavelength used. The level increases at certain wavelengths as a result of certain impurities.

Despite the fact that attenuation is an issue, it is nevertheless possible to transmit data along single mode fibers for considerable distances. Lines carrying data rates up to 50 Gbps are able to cover distances of 100km without the need for amplification. But there is still a maximum distance, this is limited not only by the attenuation of the cable, but also the distortion of the light signal along the cable. In order to overcome these effects and transmit the signals over longer distances, repeaters and amplifiers are used. These devices convert the optical signal into an electrical format where it can be processed to ensure that the signal is not distorted and then converted back into the optical format. It may then be transmitted along the next state of the fiber optic cable.

An alternative approach is to use an optical amplifier. Amplifiers directly amplify the optical signal without the need to convert the signal back into an electrical format. The amplifiers consist of a length of fiber optic cable that is doped with a rare earth mineral named Erbium. The treated fibre cable is then illuminated or pumped with light of a shorter wavelength from another laser and this serves to amplify the signal that is being carried.

In view of the much reduced cost of fiber optic amplifier over repeater, most repeaters have been replaced by amplifiers, amplifiers are far more widely used.