The application of EDFA in the communication system

The main function of EDFA in the optical fiber communication system is to extend the relay distance. When it is combined with wavelength division multiplexing technology and optical arc technology, it can realize ultra-large capacity and ultra-long distance transmission.
There are mainly several applications of EDFA in communication systems:
1. As a preamplifier
For the receiver's preamplifier, a high-gain, low-noise amplifier is generally required. Due to the low-noise characteristics of EDFA, when it is used as a receiver's preamplifier, the sensitivity of the receiver can be greatly improved. Its application is shown in Figure (a).
2. Use as transmitter power amplification
If the bait-doped fiber amplifier is connected to the output of the transmitter, it can be used to increase the output power, increase the input fiber optical power, and extend the transmission distance, as shown in Figure (b).
3. Use as a repeater

This is an important application of EDFA in optical fiber communication systems. It can replace traditional optical/electrical/optical repeaters and directly amplify the optical signal in the line to achieve all-optical communication technology. The principle is shown in (c).