erbium doped fiber amplifiers principles and applications

Erbium doped fiber amplifiers principles :

EDFA stands for erbium doped fiber amplifier, An optical amplifier are also called erbium doped fiber amplifier or EDFA. This article also gives you  advantages and disadvantages of EDFA to know more details about EDFA.

The erbium atoms in silica are Er³⁺ ions with three lost electrons in its orbit. The raising of ions to higher energy levels is achieved by two pump level.

1. Meta stable state :

The meta stable state is a state from which the life time for the transitions from this state to the ground state are very long compared with the life times to the states that led to this level. 

 2. Stark splitting :

The meta stable, the pump band state and ground state levels are closely spaced energy levels form the manifold called stark splitting.

Erbium doped fiber amplifiers applications :

• Erbium doped is a double clad fibers can be used for generating very high output power of tens of watts or even more.
• It is also possible to amplify ultra short pulses in the 1.5 micro meter region to relatively high energies using EDFAs in the form of amplifier chains
• As a pump absorption efficiency can be weak in this case, an ytterbium sensitized core may again be useful.
• One exploits the relatively high saturation energy of such amplifier, particularly when erbium doped large mode area fibers.
• For proper choice of material composition of the fiber core this energy transfer can be fairly efficient.
• The use of pure erbium doped fibers is more common in the telecom area side.

Advantages and disadvantages of semiconductor optical amplifier

Semiconductor optical amplifier is one type of laser diode without end of the mirror. it is the latest technology that provides high-speed switching capability, high extinction ratio, gain etc. Here this article gives the advantages and disadvantages of semiconductor optical amplifier to know more details about semiconductor optical amplifier (SOA).

Advantages semiconductor optical amplifier :

• Small size
• Electrically pumped
• Smaller output power then EDFA
• Less expensive then EDFA
• It can be run with a low power laser
• It provides all types of nonlinear operation like cross-phase modulation, cross gain modulation can be conducted

Disadvantages of  semiconductor optical amplifier :

• Lower gain
• High non-linearity
• Higher noise
• Polarization dependence

Explore more information:

1. Advantages and disadvantages of EDFA

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.

Semiconductor optical amplifier

Introduction to semiconductor optical amplifier :

An optical amplifier is nothing but a laser diode without feedback. Which introduce in 1990. It is mainly used the inline optical amplifier. Semiconductor optical amplifier is a laser diode without an end mirror. It is a  most important technology provides high-speed switching capability, high extinction ratio, gain etc. There are many types of optical amplifier namely semiconductor optical amplifier ( SOA ) like erbium doped optical amplifier ( EDFA ), Raman amplifier. This article will make a clearer introduction to semiconductor optical amplifier ( SOA ).

Some key point in semiconductor optical amplifier :

• Similar to laser but with nonreflecting ends and broad wavelength emission.
• In this amplifier, incoming optical signal stimulates emission of light at its own wavelength.
• The process continues through the cavity to amplify a signal.
• Semiconductor optical amplifier consumes less power and it can use fewer component.
• Active medium consists of an alloy semiconductor ( Ga, P, In, As ).
• It works in both attenuation windows, 1300 nm, and 1500 nm.
• It very broad gain spectrum.
• High fiber to fiber gain 20 dB.
• Semiconductor optical amplifier has rapid gain response 1 ps to 0.1 ns.

A basic structure of SOA :

An SOA  work in a similar way to a basic laser. As a name suggested are used to amplify the optical signal. A typical structure of InGaAsP/InP structure of given below. The structure is much the same, with two specially designed slabs of semiconductor material on top of each other, with another material between them forming the active layer. The smaller bandgap intrinsic region has a smaller refractive index than the wider bandgap p doped and n doped quasineutral region. The intrinsic region forms the core of the optical waveguide and the quasi-neutral region form the claddings. Current injection into the intrinsic region can create a large population of electron and holes.

During the operation as an optical amplifier, light is coupled into the waveguide at Z=0. As the light propagates inside the waveguide it gets amplified and finally when the light at Z=L, its power is much higher compared to what it was at Z=0.

There are two major types of Semiconductor optical amplifier is :

1. Fabry Perot amplifier ( FPA )
2. Traveling wave amplifier ( TWA )

Now here this article you have to also check it out the advantages and disadvantages of semiconductor optical amplifier below :

Advantages semiconductor optical amplifier :

• Small size.
• Electrically pumped.
• Smaller output power then EDFA.
• Less expensive then EDFA.
• It can be run with a low power laser.
• In this amplifier all types of nonlinear operation like cross-phase modulation, cross gain modulation can be conducted.

Disadvantages of  semiconductor optical amplifier :

• Lower gain.
• High non-linearity.
• Higher noise.
• Polarization dependence.

Application of semiconductor optical amplifier :

• Power booster
• Inline amplifier
• Preamplifier 

What is optical amplifier

In advanced technology, an optical fiber amplifier is used in transmitting data in fiber optic communication systems. An amplifier is inserted at a specific place to boost optical signals in a system where the signal is a week. In a large network, a long series of the optical fiber amplifier is placed in a sequence along the entire network link. An optical amplifier is basically nothing but a laser without of feedback. It is a fiber optic device used to amplify optical signal directly without conversion into an electrical signal.  Optical amplification depends on the frequency of the incident signal and local beam intensity. It is a device that amplifies an optical signal without converting it into an electric signal. 

 Types of an optical amplifier called an EDFA and Raman amplifier also have their advantages and disadvantages. 

An optical amplifier is characterized by these characteristics given below  : 

• Gain - It is a ratio of output power to input power ( dB )
• Gain bandwidth of a system - Range of wavelength over which the amplifier is effective  Gain saturation of a system - Maximum output power, beyond which no amplification is effective 
• Gain efficiency of a system - Gain is a function of input power (dB/mW)
•  A noise of a system- Undesired signal due to physical processing in amplifier ''

Explore more information:

1.      Advantages and disadvantages of Raman amplifier