Take you to quickly understand what is an EDFA amplifier
906 2022-01-04
The optical fiber amplifier is an optical amplifier device that directly amplifies the optical signal in the optical fiber communication system. In a communication system using optical fibers, it is a technology that directly amplifies optical signals without converting optical signals into electrical signals.

The working principle of erbium-doped fiber amplifier The erbium-doped fiber amplifier is mainly composed of a section of erbium-doped fiber (about 10-30m in length) and a pump light source. Its working principle is: the erbium-doped fiber produces stimulated radiation under the action of the pump light source (wavelength 980nm or 1480nm), and the radiated light changes with the change of the input optical signal, which is equivalent to the input optical signal. Up zoom. Studies have shown that erbium-doped fiber amplifiers can usually get a gain of 15-40db, and the relay distance can be increased by more than 100km on the original basis. Then, people cannot help asking: Why do scientists think of using doped erbium in fiber amplifiers to increase the intensity of light waves? We know that erbium is a kind of rare earth element, and rare earth elements have their special structural characteristics. For a long time, people have been using the method of doping rare earth elements in optical devices to improve the performance of optical devices, so this is not an accidental factor. In addition, why is the wavelength of the pump light source selected at 980nm or 1480nm? In fact, the wavelength of the pump light source can be 520nm, 650nm, 980nm, and 1480nm, but practice has proved that the pump light source with a wavelength of 1480nm has the highest laser efficiency, followed by the wavelength 980nm pump light source.





The main advantages of
EDFA are high gain, large bandwidth, high output power, high pumping efficiency, low insertion loss, and insensitivity to polarization.

1. Power amplifier (booster-Amplifier), after the multiplexer, is used to boost the power of multiple wavelength signals after multiplexing, and then transmit it, because the signal power after multiplexing is generally relatively large, so, 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), before the demultiplexer, 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.