As optical signals travel through the fiber, the signals become weaker in power. Until it becomes too weak to be detected reliably, the farther you go, the weaker the signal becomes.
By using fiber amplifiers along the way, Fiber-optic communication systems and Optical Switch solve this problem. At a point where the signal has become weak, an amplifier or repeater is inserted into the system to boost the strength of the signal so, through another length of fiber cable, it can be transmitted.
To keep the signal strength along with the whole fiber link many repeaters or amplifiers can be placed in sequence.
For optical signal amplification, electronic repeaters were used traditionally. An Opto-electro-Opto device is a repeater. With a light wave transmitter, It converts the electronic signal back to the optical signal after converting a weak optical signal into an electronic signal, cleaning up the electronic signal. As compared to the incoming optical signal, the light wave transmitter emits much stronger power and thus amplifies it.
A purely optical device is an optical fiber amplifier. To electronic signal, it doesn’t convert the incoming optical signal at all. Basically, it can indicate by an in-line laser. Dozens of optical channels can be amplified by an Optical Amplifier simultaneously since into electronic signals, they do not convert each channel separately.
Doped with a rare-earth element such as praseodymium or erbium, Optical fiber amplifier is a section of optical fiber.
For an optical fiber communication system, this is a very convenient form of amplifier since it is an in-line amplifier, thus removes the need for an electrical-optical conversion process and to do the optical-electrical.
For the operation of fiber amplifiers, key parameters are the corresponding optical signal wavelengths and the Pump Combiner. Doped in the fiber, these wavelengths depend and also von the type of rare-earth element. The gain saturation effect comes into play for high input powers.
Fiber MART 