Today, optical fiber cable networks have spread all over the world, and optical fiber communication has become an important pillar of the "information highway". However, due to the transmission loss of the optical fiber itself, the optical signal can only be transmitted not too far away, and it will be attenuated to the extent that the receiver cannot distinguish it. In the past, the optical relay used the "optical-electric-optical" method for optical amplification. A revolution in optical communication technology caused by the advent of EDFA plays an important role in post and telecommunications, cable television and computer network systems that use optical fiber as the transmission medium.

Classification of EDFA erbium-doped fiber amplifier:

1. Power amplifier (booster-Amplifier), after the multiplexer, is used to boost the power of multiple wavelength signals after multiplexing, and then transmit, because the signal power after multiplexing is generally relatively large,
Therefore, the noise figure and gain requirements of a power amplifier are not very high, but it is required to have a relatively large output power after amplification.

2. Line-Amplifier (Line-Amplifier), after the power amplifier, is used to periodically compensate the line transmission loss. Generally, a relatively small noise index and a relatively large output optical power are required.

3. The pre-amplifier (Pre-Amplifier), located before the demultiplexer and after the line amplifier, is used for signal amplification to improve the sensitivity of the receiver (when the optical signal-to-noise ratio (OSNR) meets the requirements, larger input power It can suppress the noise of the receiver itself and improve the receiving sensitivity), the noise figure is required to be very small, and there is not much requirement on the output power.

A revolutionary breakthrough in the field of optical fiber communication, it makes long-distance, large-capacity, and high-speed optical fiber communication possible. It is an indispensable important device for DWDM systems, future high-speed systems, and all-optical networks. Its research, development and application are of great significance to the development of optical fiber communications.

The main function is to compensate the power of the signal light in the transmission link.