Download Steady State Simulation of Semiconductor Optical Amplifier

Steady State Simulation of
Semiconductor Optical Amplifier
by
Mr. Abdulrahman Alosaimi
Outline
•
•
•
•
•
•
•
•
•
Introduction
Basic Descriptions of Optical amplifier
Types of Semiconductor Optical Amplifiers
Optical Amplifications Principles
Physical Structure of Semiconductor Optical Amplifier
Numerical Simulation and Algorithms
Travelling Wave Equations for Signal Fields
Travelling Wave Equations for Spontaneous Emission
Carrier Density Rate Equation
• Steady State Numerical Algorithm
• Results
Introduction
Basic Descriptions of Optical amplifier
• An SOA is an optoelectronic device that under suitable operating
conditions can amplify an input light signal.
• A schematic diagram of a basic SOA is shown in Fig. (A).
• The active region in the device imparts gain to an input signal.
• An external electric current provides the energy source that enables
gain to take place.
Types of Semiconductor Optical Amplifiers
• The Fabry Perot SOA (FP-SOA) where reflections from the end facets
are significant (i.e. the signal undergoes many passes through the
amplifier).
• The travelling-wave SOA (TW-SOA) where reflections are negligible
(i.e. the signal undergoes a single-pass of the amplifier). Antireflection coatings can be used to create SOAs with facet reflectivities
The TW-SOA is not as sensitive as the FP-SOA to fluctuations in bias
current, temperature and signal polarization.
Optical Amplifications Principles
Physical Structure of Semiconductor Optical Amplifier
Fig. : Double-heterostructure (DH) semiconductor Optical Amplifiers
Numerical Simulation and Algorithms
• The model is based on a set of coupled differential
equations that describe the interaction between the
internal variables of the amplifier
• Travelling Wave Equations for Signal Fields
• Travelling Wave Equations for Spontaneous Emission
• Carrier Density Rate Equation
Travelling Wave Equations for Signal Fields
Es+ and Es- propagating in the positive and negative z directions respectively,
z lies along the amplifier axis with its origin at the input facet.
where 𝒋 = −𝟏 and α is the material loss coefficient
Г is optical confinement factor
β signal propagation coefficient
gm(ѵ,n) material gain coefficient
Travelling Wave Equations for Spontaneous
Emission
N+, N- are defined as the spontaneous emission photon rates (1/sec)
Rsp represents the spontaneously emitted noise coupled into N+, N-
Carrier Density Rate Equation
The carrier density n(z) obeys the rate equation
I is the amplifier bias current
e is the electronic charge
d is SOA thickness
L is SOA active region length
W is SOA active region width
R(n) contain the radiative and
nonradiative carrier
recombination rate
Steady State Numerical Algorithm
• The amplifier is split into a number of sections. The signal fields and
spontaneous emission photon rates are estimated at the section
interfaces. The carrier density is estimated at the centre of each
section.
Results
Predicted SOA output spectrum
versus wavelength
predicted gain profile with input
signals
Optical spectrum analyser display of SOA output. Resolution bandwidth = 0.1 nm
Optical spectrum analyser display of SOA output. Resolution bandwidth = 0.1 nm
-10
-10
-15
-15
Power (dBm)
-20
Power (dBm)
-20
-25
-25
-30
-30
-35
-35
-40
1500
1510
1520
1530
1540
1550
1560
Wavelength (nm)
-40
1500
1510
1520
1530
1540
1550
1560
Wavelength (nm)
1570
1580
1590
1570
1580
1590
• Predicted forward and backward signal propagation as a function of
spatial distribution