Every software package contains a full set of examples suitable for that version and are installed with the software. If you see examples here that are not in your installation you should consider updating to a later version of the software. These examples can be used by beginners and advanced users for product evaluation, teaching purposes, and self-training.

Required Modules

Atlas

• Blaze
• Laser

This example demonstrates simulation of a buried heterostructure InP/InGaAsP laser diode. A physically based frequency dependent optical gain model is used in this example to calculate light emission spectrum.

The example shows:

Laser structure definition using Atlas syntax

Setting up the device models and initial biasing

Activating LASER module of Atlas

Mesh definition for solving the Helmholtz wave equation

Definition of laser physical models and their parameters including the frequency dependent optical gain model

Calculation of laser electrical and optical characteristics

This example illustrates how Atlas can be used to simulate spectral characteristics. The spectral characteristics refer to the longitudinal laser spectrum since LASER considers only the fundamental transverse mode solution. It is known from the theory that the longitudinal laser spectrum depends on the optical gain, spontaneous emission spectrum, and the cavity length in the third dimension (or Z-direction). A shorter cavity length leads to a wider energy spacing between adjacent longitudinal modes, and so fewer longitudinal modes will be lasing. From the computational point of view the situation of the nearly single mode laser operation is very desirable because each lasing mode considered imposes an additional computational burden.

Here, physically based optical gain modes are activated in LASER simulation using the syntax models lmodes gainmod=1. Gainmod=1 sets the frequency dependent model. The parameters las_einit las_efinal are used to specify the photon energy range for spectral analysis, and the cavity_length parameter is set to 50 microns. The latter value is rather small, but it allows us to demonstrate the spectral analysis within a comparatively short run time.

The additional variables specified in the output statement will be saved in the output structure file. These include the conduction and valence band potentials for analysing the energy band diagram, total, SRH, Auger, and radiative recombination rates, and current flowlines.

During simulation the IV data, light power, and total optical gain data is stored in the log file. The laser spectra (gain spectra and photon density spectra) are stored in separate log files for each bias condition. The name of the spectrum log file is specified using the parameter spec.name in the models statement in the LASER portion of the input file.

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