Basics of Optical amp, a brief explanation on how a Raman OP works. You must know What is Scattering, stimulated and spontaneous emission in order to understand the basic principal of this OP amp. Pump is also important which is the one that stimulates the energy to higher levels.

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Raman optical amplifiers
By: Eng. Donaire Carapichoso

2.  An Optical Fibre system in order to transmit signals
overlong distances it is necessary to compensate for
attenuation losses within the fibre
 Semiconductors devices can convert an optical signal
into an electrical signal, amplify it and reconvert the
signal back to an optical signal. However this
procedure has several disadvantages
 Engineers developed what is called Optical Amplifier
which amplifies the optical signal directly, without
ever changing it to electrical signal. The light itself is
amplified
Introduction

3.  In this presentation we will focus on Raman Optical
Amplifier and Because of severe limitations such as
narrow linewidth, and almost the same operation as
the Raman, Brillouin fibre amplifiers will not be
treated henceforth .
Introduction (cont)
Basic diagram of an optical amplifier

4. Raman Amplifier
The Raman amplifier in order to amplify the
optical signal it makes use of a
process/phenomenum called scattering.
Scattering
• Raman scattering (one of the types of
scattering)

5.  In simple terms in raman scattering a molecule
absorbs light, goes up to a virtual state and falls
back down to a final state which is different to the
inicial state. When it emits energy as it falls back
down, the frequency or the energy of the light is
going to be different to the incoming light.
Raman scattering (Basic
concepts)
 Consider a material which are having energy
levels

6. Raman Scattering
 Stimulated Raman Scattering
(The one used for Optical amplification)
 Spontaneous Raman Scattering
Raman scattering (Basic
concepts cont…)

7.  Use stimulated Raman effect and pump laser whose
frequency is equal to signal frequency plus
frequency of chemical bond in the material and
because it is a nonlinear process, requires very high
pump powers (watts)
 A Raman amplifier is a device which takes input 𝜔𝑠
and amplified in the same direction or opposite
direction with pump laser 𝜔𝑃.
Raman amplifier
(Working principal)

8. There are basically two types of Raman
amplifiers as given here:
 Distributed Raman Amplifier (DRA): uses the
transmission fiber itself as the medium, into
which a backward pump is injected.
 Discrete (Lumped) Raman Amplifier (RA): The amplifier
consists of a coil of dedicated fiber together with pumps.
Advantages:
• Low noise (3–5 dB).
• Wide gain bandwidth (up to 10 nm).
• Distributed amplification within the transmission fiber.
Limitations:
 • Low gain (10 dB).
 • Requirement of high pump power.
Types of Raman amplifier

9. In conclusion to this presentation we pin point
the most important things concerned about the
Raman Amplifier
 It make uses of a scattering process, to be
specific Simulated Raman Scattering
 They are two types :
Distributed Raman Amplifier (DRA
Discrete (Lumped) Raman Amplifier (RA)
Conclusion