Erbium doped fiber amplifier

Introduction of Erbium-doped fiber amplifier :

EDFA stands for erbium-doped fiber amplifier, An optical amplifier or types are also called erbium-doped fiber amplifier or EDFA. An Erbium-doped fiber amplifier is an optical amplifier that amplified a modulated laser beam directly, without electron-optical or optoelectronic conversion. The most popular material for long-haul telecommunication application widely used in silica doped with erbium, which is known as Erbium doped fiber amplifier or EDFA. Here this article to give a brief introduction to the most deployed fiber amplifier called the erbium-doped fiber amplifier.

Working principle :

Amplification mechanism : 

The operation of an EDFA by itself normally is limited to the range of 1530 to 1560 nm region. The energy level diagram of erbium ions in silica is shown in the figure.
Erbium-doped fiber amplifier
The erbium atoms in silica are called Er3+ ions with three lost electrons in its orbit. The raising of ions to higher energy levels is achieved by two types of pump level.

1. Metastable state :
The metastable state is a state from which the lifetime for the transitions from this state to the ground state is very long compared with the lifetimes to the states that led to this level. 

 2. Stark splitting :
The metastable, the pump band state and ground state levels are closely spaced energy levels form the manifold called stark splitting.


Energy level diagram 


This article also gives the advantages and disadvantages of EDFA below :

Advantages of EDFA :
  • Gain is an excess of 40 to 50 dB.
  • Low noise 3-5 dB, it is suitable for the long haul application.
  • High pump power utilization.
  • It is fully compatible with the rest of the fiber optic transmission link.
  • Flatness can be improved gain flattening optical filter.
  • Amplify wide wavelength band in the range of 1530 nm to 1560 nm region, with a relatively flat.
Disadvantages of EDFA :
  • Size of EDFA is large. 
  • High pump power consumption.
  • It cannot be integrated with other semiconductor devices.

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