167 research outputs found
Modeling and efficient simulations of broad-area edge-emitting semiconductor lasers and amplifiers
We present a (2+1)-dimensional partial differential equation model for spatial-lateral dynamics of edge-emitting broad-area semiconductor devices and several extensions of this model describing different physical effects. MPI-based parallelization of the resulting middlesize numerical problem is implemented and tested on the blade cluster and separate multi-core computers at the Weierstrass Institute in Berlin. It was found, that an application of 25-30 parallel processes on all considered platforms was guaranteeing a nearly optimal performance of the algorithm with the speedup around 20-25 and the efficiency of 0.7-0.8. It was also shown, that a simultaneous usage of several in-house available multi-core computers allows a further increase of the speedup without a significant loss of the efficiency. Finally, an importance of the considered problem and the efficient numerical simulations of this problem were illustrated by a few examples occurring in real world applications
Traveling wave modeling of dynamics in semiconductor ring lasers
We use the traveling wave model for simulating and analyzing nonlinear dynamics of complex semiconductor ring laser devices. This modeling allows to consider temporal-spatial distributions of the counter-propagating slowly varying optical fields and the carriers, what can be important when studying non-homogeneous ring cavities, propagation of short pulses or fast switching. By performing numerical integration of the model equations we observe several dynamic regimes as well as transitions between them. The computation of ring cavity modes explains some peculiarities of these regimes
Numerical bifurcation analysis of traveling wave model of multisection semiconductor lasers
Traveling wave equations are used to model the dynamics of multisection semiconductor lasers. To perform a bifurcation analysis of this system of 1-D partial differential equations its low dimensional approximations are constructed and considered. Along this paper this analysis is used for the extensive study of the pulsations in a three section distributed feedback laser. Namely, stability of pulsations, different bifurcation scenaria, tunability of the pulsation frequency and its locking by the frequency of electrical modulation are considered. All these pulsation qualities are highly important when applying lasers in optical communication systems
Calculation of the steady states in dynamic semiconductor laser models
We discuss numerical challenges in calculating stable and unstable steady states of widely used dynamic semiconductor laser models. Knowledge of these states is valuable when analyzing laser dynamics and different properties of the lasing states. The example simulations and analysis mainly rely on 1(time)+1(space)-dimensional traveling-wave models, where the steady state defining conditions are formulated as a system of nonlinear algebraic equations. The performed steady state calculations reveal limitations of the Lang-Kobayashi model, explain nontrivial bias threshold relations in lasers with several electrical contacts, or predict and explain transient dynamics when simulating such lasers
A multi-mode delay differential equation model for lasers with optical feedback
In this paper, we discuss the relations between the
spatially-distributed traveling wave, Lang-Kobayashi, and a new multi-mode
delay differential equation models for Fabry-Perot type semiconductor diode
lasers with an external optical feedback. All these models govern the
dynamics of the slowly varying complex amplitudes of the optical fields and
carrier density. To compare the models, we calculate the cavity modes
determined by the threshold carrier density and optical frequency of the
steady states in all three models. These calculations show that the
Lang-Kobayashi type model is in good agreement with the traveling wave model
only for the small feedback regimes, whereas newly derived multi-mode delay
differential equation model remains correct even at moderate and large
optical feedback regimes
Longitudinal modes of multisection ring and edge-emitting semiconductor lasers
We use the traveling wave model for simulating and analyzing nonlinear dynamics of multisection ring and edge-emitting semiconductor laser devices. We introduce the concept of instantaneous longitudinal optical modes and present an algorithm for their computation. A semiconductor ring laser was considered to illustrate the advantages of the mode analysis
Traveling wave modeling of nonlinear dynamics in multisection semiconductor lasers
A hierarchy of 1 (time) + 1 (space) dimensional first-order partial differential equation (traveling wave) models is used for a description of dynamics in individual semiconductor lasers, various multisection semiconductor lasers, and coupled laser systems. Consequent modifications of the basic traveling wave model allow for taking into account different physical effects such as the gain dispersion, the thermal detuning, the spatial hole burning of carriers, the nonlinear gain saturation, or various carrier exchange processes in quantum dot lasers. For illustration, the model was applied for simulations of dynamics in complex ring laser with four branches of filtered feedback. Finally, several advanced techniques for model analysis such as calculation of instantaneous optical modes, finding of steady states, and numerical continuation and bifurcation analysis of the model equations were discussed and illustrated by example simulations
Sampling techniques applicable for the characterization of the quality of self pulsations in semiconductor lasers
The aim of the presented report is to demonstrate how the sampling techniques can be used to characterize the quality of self pulsations in a multi-section semiconductor laser and the synchronization of self pulsations with an optical or electrical periodically modulated signal. The developed tools are described and some examples are given
Calculation of steady states in dynamical semiconductor laser models
We discuss numerical challenges in calculating stable and unstable steady states of widely used dynamical semiconductor laser models. Knowledge of these states is valuable when analyzing laser dynamics and different properties of the lasing states. The example simulations and analysis mainly rely on 1(time)+1(space)-dimensional traveling-wave models, where the steady state defining conditions are formulated as a system of nonlinear algebraic equations. The per- formed steady state calculations reveal limitations of the Lang-Kobayashi model, explain nontrivial bias threshold relations in lasers with several electrical contacts, or predict and explain transient dynamics when simulating such lasers
Modeling and efficient simulations of broad-area edge-emitting semiconductor lasers and amplifiers
We present a (2+1)-dimensional partial differential equation model for
spatial-lateral dynamics of edge-emitting broad-area semiconductor devices
and several extensions of this model describing different physical effects.
MPI-based parallelization of the resulting middlesize numerical problem is
implemented and tested on the blade cluster and separate multi-core computers
at the Weierstrass Institute in Berlin. It was found, that an application of
25-30 parallel processes on all considered platforms was guaranteeing a
nearly optimal performance of the algorithm with the speedup around 20-25 and
the efficiency of 0.7-0.8. It was also shown, that a simultaneous usage of
several in-house available multi-core computers allows a further increase of
the speedup without a significant loss of the efficiency. Finally, an
importance of the considered problem and the efficient numerical simulations
of this problem were illustrated by a few examples occurring in real world
applications
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