What is EDFA?

EDFA is an optical repeater device that is generally used in the C and L bands, almost between 1530 and 1565nm.The fiber is doped with the rare earth element erbium, allowing the glass fiber to absorb light at one frequency and emit light at another frequency.At present, EDFA optical fiber communication is usually used to compensate for the optical fiber loss in long-distance optical communication. Its power transmission efficiency, large dynamic range, low noise number and no polarization are high, which is an ideal solution for wave-division and multi-channel (WDM) applications and long-distance applications.

How does EDFA work?

The basic structure of an EDFA consists of a length of Erbium-doped fiber (EDF), a pump laser, and a WDM combiner. The WDM combiner is used to combine signals and pump wavelengths, allowing them to propagate simultaneously through the EDF.

For example, 1550nm light signal, into the EDFA amplifier from the input. The 1550nm signal combines with 980nm pump laser and WDM——signal and pump laser through a section of erbium-doped fiber, and the 1550nm signal is amplified by interaction with doped erbium ions. This action amplified the weak optical signal to a higher power, thereby increasing the signal intensity.

What are the types of EDFA?

According to its position and function in the system, EDFA can be divided into Booster Amplifier, In-line Amplifier and Pre-Amplifier.

1.Booster Amplifier

The booster amplifier works on the transmission side of the link, is placed behind the transmitter, and is used to increase the power of multiple wavelengths signals after the wave closing, and then transmit it. Because the signal power after the wave is generally relatively large, the noise index and gain requirements of the booster amplifier are not very high, but they require a relatively large output power after amplification.

2.In-line Amplifier

The In-line amplifier is usually set along the middle point of the transmission link in the DWDM link to overcome the fiber transmission and other distributed losses. The In-line amplifier is designed to amplify light between two network nodes on the primary optical link. The In-line amplifier is placed every 80-100km to periodically compensate the line transmission loss. Generally, it requires relatively small noise index and large output optical power.

3.Pre-Amplifier

The pre-amplifier operates at the receiving end of the DWDM link. The pre-amplifier is used to compensate for the loss in the demultiplexer near the optical receiver, placed before the receiver end of the DWDM link, and used to enhance the signal level before optical detection in the ultra-long distance system, so as to improve the receiving sensitivity (if OSNR meets the requirements, the large input power can suppress the noise of the receiver itself, and improve the receiving sensitivity). The noise index is small and there is no requirement for the output power.

PS：FiberWDM’s EDFA Optical Amplifier is low-noise, gain-flattened C-band optical erbium doped fiber amplifier (EDFA) designed to cost-effectively extend the optical link power budget for building long distance solutions.

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