Optical Amplifier-EDFA (Erbium Doped Fiber Amplifier)-Why do we need it?

Optical amplifiers are indispensable in the optical fiber network communication system. But before explaining what is an optical amplifier, especially the optical amplifier EDFA and why it is so important in the fiber communication field, we have to understand how does the optical fiber signal transmission works.

We have the idea that the network intercommunication happens because of the fiber optical technology. In the fiber optical technology, the fiber optical cable is responsible to transmit light signal from an end-to-end optical network, by encoding this signals with data information. The data information coded in the beam light navigates down the fiber cable core in long distance and high speed. When this optical fiber light signals are transmitted in a long distance it may occur transmission loss of the light signal, which can cause a weakening of the signal power. Particularly, that is when we need to use an optical amplifier to amplify the light signal to compensate the transmission loss of the signal power in a long distance optical fiber intercommunication system.

What is an Optical Amplifier ?

An optical amplifier is an essential device used to amplify optical signals instantaneously without having the need to convert this optical signals into electrical signals, especially in long distance fiber optical network communication system.

Among the several different types of optical amplifiers existing, such as SOA(semiconductor optical amplifier), FRA(fiber raman amplifier), Brillouin amplifier and the EDFA(erbium doped fiber amplifier), generally the one most chosen in most applications is the EDFA( Erbium doped fiber amplifier) .

EDFA (Erbium Doped Fiber Amplifier)

EDFA (Erbium doped fiber amplifier) is an optical amplifier designed with a rare earth element called erbium ions inside the core of the optical fiber. The use of the erbium ions in the optical fiber core help to increase the optical amplification of the signal power, which also increase the energy level and the bit-rate of the signal transmission.

Widely, EDFA amplifier is the mainly one used in the WDM( wavelength division multiplexing) system. Usually, it is utilized in C band and L band. It is mostly utilized to compensate the transmission loss of long distance optical fiber communication. One of the main features about the EDFA is that it has the capacity of amplifying several optical signal at the same time.

How does it the EDFA works ?

As i already mentioned before, Erbium Doped Fiber Amplifiers (EDFA) are developed with erbium doped fiber (EDF) inside the fiber core, which positively aids in the fiber absorption of light signal at one frequency and discharge at another frequency. The EDFA basic structure is composed of a erbium doped fiber, a pump laser and the WDM component, that it used as a combiner between the signal and the pump wavelength.

 EDFA operational principle

When an optical signal, as for instance a 1550nm signal, go into a EDFA amplifier through the input. This signal is combined and pumped with a 980mn pump laser by a WDM component, in which the signal and the pump laser passes through the extent of the erbium ions fiber core. The signal is directly amplified across the doping erbium ions core. This interaction helps to amplify a weak optical signal intro a high signal power, in which can increase the signal length. This process is described as amplification.

The EDFA (Erbium Doped Fiber Amplifier) application

  • Booster amplifier.

The Booster amplifier works on the transmission part of the optical link, and is an important element in the DWDM link where the signal channels are attenuated by the multiplexer. Booster amplifiers are projected to amplify optical input power intro the link at a required extension, and it includes high input power, high output power and medium optical gain.

  • Line amplifier

The Line amplifier works in the midway part of the optical link, and operates as a support for the fiber transmission loss. Line amplifier are projected for optical amplification of two linked networks nodes on core optical link, and it includes medium to low input, high output power, low noise figure and high optical gain.

in-line optical amplifier

in-line optical amplifie

  • Pre-amplifier

The Pre-amplifier works at the optical link termination, and it operates as a support for the transmission loss that may occur along the optical receiver. Pre-amplifier are projected at the receiving termination of the optical link, and it includes a low input power a medium output power and a medium gain.

fiber optic pre-amplifier

fiber optic pre-amplifier

Why do we need the EDFA (Erbium Doped Fiber Amplifier)?

The use of EDFA have several advantages in the application field of optical communication system:

  • EDFA operates in the high capacity and high speed optical network communication system.
  • EDFA can be used in long distance network system.
  • It works as tool to compensate the transmission loss that usually happens in long distance transmission system.
  • The integration of EDFA and WDM(wavelength division multiplex)/DWDM(dense wavelength division multiplex) aids to fix issues of insertion loss and chromatic dispersion the beam lights.

The optical amplifier EDFA is an essential device in many domain applications of the optical fiber communication  system, especially the long distance transmission system. Since it is projected to directly help the amplification of optical signal, and significantly reduce the transmission loss of the optical signal as well.

Related articles:
The Application of EDFA
Optical Fiber Amplifier – EDFA (Erbium-doped Fiber Amplifier) for FTTH WDM system

Post time: 2022-04-07


Lomoveishiy – Finland

I needed those to connect my PC on the third floor to have internet access in that room, and ISP installed their modem on the first floor only. After dropping fiber patch cables, plugged in all cables into these media converters at both sides, and link came up instantly. Was much easier than I thought!

Raymond – USA

Great experience – units worked straight out of the box – just needed plug in cables and we were done. I also like the possibility to enable jumbo frames, while we do not have a need for this feature at the current moment it’s great to have this option.

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