Steady State Simulation of Semiconductor Optical Amplifier by Mr. Abdulrahman Alosaimi

Outline Steady State Numerical Algorithm 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). Anti- reflection 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 gain profile with input signals Predicted SOA output spectrum versus wavelength predicted gain profile with input signals

Predicted forward and backward signal propagation as a function of spatial distribution