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What is an EDFA Optical Amplifier?
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What is an EDFA Optical Amplifier?

Views:0     Author:Site Editor     Publish Time: 2021-05-13      Origin:Site

What is an EDFA Optical Amplifier?

EDFA optical amplifier, also known as erbium-doped fiber amplifier, is a kind of special fiber with the rare earth element erbium injected into the fiber core. It was first developed by the University of Southampton in 1985. Since the late 1980s, the research of EDFA has made great breakthroughs. At present, EDFA has become the most widely used optical amplifier in optical fiber communication.


Here is the content list:

What is the structure of the EDFA optical amplifier?

What is the working principle and process of EDFA?

What is the classification of EDFA?


What is the structure of the EDFA optical amplifier?

The main part of the EDFA optical amplifier consists of erbium-doped fiber (EDF), pump light source, optical coupler, optical isolator and optical filter and other structures.

First of all, erbium-doped fiber is a kind of fiber doped with a small amount of rare earth element erbium ions in the quartz fiber. The length of this fiber is generally between 10 meters and 100 meters, which is the core structure of the EDFA optical amplifier. Secondly, if we need to activate the erbium-doped fiber, we need an external excitation source, which is the pump light source. The optical coupler can couple the light emitted from the pump light source and turned from different directions into the same fiber.

In addition to these essential devices, an optical isolator is required on both sides of erbium-doped optical fibers. Its function is to isolate backscattered light and to ensure that erbium-doped optical fibers work in a stable environment and are not affected by other stray light. An optical filter is also needed. In addition to filtering out noise and improving the signal-to-noise ratio of the system, an optical filter also needs to filter out the light emitted by the pump light source so that the output light signal is the same frequency as the input light signal.


What is the working principle and process of EDFA?

The basic working principle of the EDFA optical amplifier is the same as that of the semiconductor lasers. The reason why EDFA optical amplifier can amplify the optical signal is that under the action of the pump light source, the particle number inversion distribution appears in the erbium-doped fiber, resulting in stimulated radiation, so that the optical signal is amplified.

The erbium ion has three working levels: ground state, metastable state and excited state. When the fiber is continuously excited by the laser of the pump source, the particles in the ground state gain energy and then transfer to the high energy level. Because the particle is not stable at the high energy level of the excited state, it will quickly fall to the metastable state by a nonradiative transition process, and the particle has a relatively long lifetime at this energy level. At this point, the number of particles in the metastable state level is increasing due to the continuous excitation of the pump source, while the number of particles in the ground state level is decreasing. In this way, the inversion of particle number distribution is realized in this erbium-doped fiber, and the conditions for optical amplification are provided.

When the photon energy of the input optical signal is equal to the energy difference between the metastable state and the ground state, the metastable particles will jump to the ground state in the form of stimulated radiation and emit the same photons as the photons in the input optical signal. In this way, the number of photons in erbium-doped fiber increases greatly, the input optical signal becomes a strong output optical signal, and the optical signal is amplified.


What is the classification of EDFA?

EDFA has three different configurations depending on how the light source is pumped.

The first is a co-pumped EDFA optical amplifier, which means that both the pump light source and the input light signal are injected into erbium-doped fiber in the same direction. The second type is the reverse-pumped EDFA optical amplifier, which means that the pump light source and output light signal are injected into Erbium-doped fiber from two opposite directions. The last one is the bidirectional pump EDFA optical amplifier, which combines the above two structures and simultaneously has the same pump and the reverse pump.


EDFA optical amplifier is one of the greatest inventions in optical fiber communication. Its birth is a revolutionary breakthrough in the field of optical fiber communication, which makes long-distance, large capacity and high-speed optical fiber communication possible. Hengchi Electronic Equipment Co., Ltd. has more than 14 years of experience in the design of complex optical fiber and electronic circuits. All its products can stably serve in optical fiber communication projects and obtain a high evaluation. If you are engaged in EDFA optical amplifier industry, you can consider our cost-effective products. 

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