Optical Amplifiers and their Uses

Jun 17 • Notes • 2814 Views • 2 Comments on Optical Amplifiers and their Uses

OPTICAL AMPLIFIERS AND THEIR USES

OPTICAL AMPLIFIERS:-

TYPES OF OPTICAL AMPLIFIERS:-

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1) Erbium Doped Fiber Amplifiers (EDFA):-
–All the optical amplifiers are doped with rare earth metals like erbium and yettribium. The erbium doped amplifiers are used in the C-band.In the L-band these amplifiers have less efficiency.However with modern designs these find use in the L-band also.

2) Raman Amplifiers:-
– These are used in conjunction with the erbium doped amplifiers.They are based on the principle of Stimulated Raman Scattering.

-These make use of the transmission medium as amplifiers.

3) Semiconductor Optical Amplifiers
–Semiconductor optical amplifiers are advantageous to use as they can be easily doped with the transmission medium.

-They are based on the operating principle of the laser diodes.

-These can operate in all bands ranging from O-band to U-band.

BASIC APPLICATIONS:-

It is used in point-to-point optical fiber links and multiaccess network to compensate for signal-splitting losses.
– It is used :-
1.In line optical amplifier
2. It is used as a front-end preamplifier for an optical receiver.
3. It increases the transmission distance by 10 to 100 km depending on the amplifier gain and fiber loss. .
ERBIUM DOPED FIBRE AMPLIFIER:-
–All the optical amplifiers are doped with rare earth metals like erbium and yettribium The erbium doped amplifiers are used in the C-band.In the L-band these amplifiers have less efficiency.However with modern designs these find use in the L-band also.

Amplification mechanism:
– Mechanism is done by optical pumping.

– Photons are used to raise electrons into excited states.
– Here three energy levels are used in which the electron lie at the top level.
– At the excited state, the electron releases some of the energy..
– From this level the electron releases its remaining energy in the form of a new photon with an identical wavelength as the signal photon.

 Noise:-

– The principal source in noise in amplified spontaneous emission which has a spectrum same as the gain spectrum of the amplifier.

– Noise in EDFA is 3dB while in practical amplifier the noise is 6-8 dB.
EXPECTED QUESTIONS WITH ANSWERS.
1) WHAT ARE OPTICAL AMPLIFIERS AND WHAT ARE ITS TYPES?
Ans:-
Optical amplifiers are used both in point to point link and other multinetworks.The main use of using optical amplifiers is that the need of repeaters in the link is avoided.This is not only economical but also advantageous..

2) Raman Amplifiers:-

– These are used in conjunction with the erbium doped amplifiers.They are based on the principle of Stimulated Raman Scattering.

-These make use of the transmission medium as amplifiers.

3) Semiconductor Optical Amplifiers

–Semiconductor optical amplifiers are advantageous to use as they can be easily doped with the transmission medium.

-They are based on the operating principle of the laser diodes.

-These can operate in all bands ranging from O-band to U-band.

2) WHAT ARE THE USES OF OPTICAL AMPLIFIERS?

Ans:- – It is used in point-to-point optical fiber links and multiaccess network to compensate for signal-splitting losses.
– It is used :-
1.In line optical amplifier
2. It is used as a front-end preamplifier for an optical receiver.
3. It increases the transmission distance by 10 to 100 km depending on the amplifier gain and fiber loss. .

3) WHAT IS EDFA?
Ans:- –All the optical amplifiers are doped with rare earth metals like erbium and yettribium.The erbium doped amplifiers are used in the C-band.In the L-band these amplifiers have less efficiency.However with modern designs these find use in the L-band also.

Architecture:
– An EDFA consists of an erbium-doped fiber, one or more pump lasers, a passive wavelength coupler, optical isolators and tap couplers.
-The WSC handles either 980/1550-nm or 1480/1550-nm wavelength combinations to couple both the pump and signal optical powers efficiently into the fiber amplifier.
– The tap couplers are used on both sides of the amplifier to compare the incoming signal with the amplified output.
– The isolators prevent the amplified signal from reflecting into the device.
4) EXPLAIN THE AMPLIFICATION MECHANISM OF EDFA?
Ans:- Amplification mechanism:
– Mechanism is done by optical pumping.
– Photons are used to raise electrons into excited states.
– Here three energy levels are used in which the electron lie at the top level.
– At the excited state, the electron releases some of the energy..
– From this level the electron releases its remaining energy in the form of a new photon with an identical wavelength as the signal photon.

5) WHAT IS AMPLIFICATION NOISE?
Ans:- The principal source in noise in amplified spontaneous emission which has a spectrum same as the gain spectrum of the amplifier.

– Noise in EDFA is 3dB while in practical amplifier the noise is 6-8 dB.

GATE Syllabus-

1. Gate syllabus for Electronics and Communication Engineering

2. Gate syllabus for Electrical Engineering

3. Gate syllabus for Instrumentation Engineering

IES Syllabus

1. IES Syllabus for Electronics and Telecomm

2. IES Syllabus for Electrical Engineering

amplification mechanismsOPTICAL AMPLIFIERS AND THEIR APPLICATIONSOPTICAL AMPLIFIERS-EDFATypes of optical amplifers

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