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
- Quantum
This example demonstrates the application of Laser to simulate a multi-quantum well laser diode. The key points of this simulation are:
One mesh for both electrical and laser simulations
Laser structure definition using Atlas region syntax
Optical and electrical material parameters specification for the chosen materials
Application of the QWELL parameter for active layer creation and quantum well simulation
Use of LASER statement to define laser attributes
The same BLAZE mesh used for both electrical and laser simulations
This example is derived from published work [IEEE Journal of Quantum Electronics, VOL. 34, NO. 9, September 1998] and is reproduced as closely as possible in this simulation.
Mesh Creation
The standard Atlas mesh is used in both the electrical and laser parts of this simulation. If no specific laser mesh is created, then Laser defaults to the standard Atlas mesh.
Region Creation
The REGION statements are used to define many region quantities. The material type is defined with the material parameter and the composition fractions within this material are set using the X.COMP and Y.COMP parameters appropriately.
The doping type and concentration are also defined on the region statement where the parameters acceptor and donor are used to define a uniform concentration in each region. If a non-uniform concentration is required, then the DOPING statement would need to be used instead.
Material Parameters
The material statement is used to set various physical quantities for each material region in the device. The band gap, conduction and valence band density of states and band alignment are declared with the parameters eg300, NC300, NV300 and align. The material permittivity for the solution of Poisson’s equation and the high frequency bulk dielectric constant are both explicitly set with the parameters permittivity and epsinf. Finally, the material lifetimes taun0 and taup0 and the constant of radiative recombination COPT are defined.
Quantum Wells (QWELL)
The qwell parameter of the models statement firstly creates new material region(s) that will contain the quantum wells. Both the individual barrier width wb and the quantum well width ww need to be defined. Then a solution is found for bound state energies in the quantum well by a solution to a coupled set of Poisson / Schrodinger equations. The solution to this equation is then used in the yan model to calculate the optical gain of the quantum well.
Laser and Physical Models
The physical models may be chosen from the manual as normal and in this simulation, there are 3 key models. The fermi model is chosen to correctly simulate population inversion statistics within the active region. The laser gain model chosen for the active regions is the multiple quantum well model chosen with the gainmod=4 parameter. Finally, the spontaneous recombination model optr has been chosen to calculate the spontaneous recombination in the device. The spontaneous recombination is used in the photon rate equations to calculate the photon density.
The solution to the Helmholtz equation is controlled by parameters on the laser statement. On this line the rear and front reflectivity can be defined with the rf and rr parameters. The length of the laser cavity must be defined, so that the longitudinal modes can be calculated correctly, using the cavity.length parameter.
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