The multiquantum well (MQW) solver is a 1D physicsbased solver for calculating optical and electronic properties of multiquantum well stacks. The solver returns the gain and spontaneous emission coefficients, as well as the electronic band diagram, band structure, and wavefunctions. The results from the MQW solver are often used as inputs for the TWLM element in INTERCONNECT to model edgeemitting semiconductor lasers or electroabsorption modulators.
The MQW solver simulation object in the finiteelement integrated design environment (FE IDE) provides a graphic user interface (GUI) for running the MQW simulations. A set of scriptbased functions (buildmqwmaterial, mqwgain, mqwindex) can also be used to run the MQW solver.
Inputs
The MQW solver requires the following information about the MQW structure:
 Thickness of each layer in the quantum well stack
 Properties of each material in the stack:
 k · p properties
 band gap
 electron/hole effective mass
 work function
 Effective refractive index of the MQW structure
 Linewidth broadening factor of the gain material
The MQW solver uses the following parameters:
 Carrier density
 Bias electric field
 Temperature
Outputs
The MQW solver returns the following results:
 Gain and spontaneous emission coefficients
 Complex refractive index of the MQW
 Electronic band diagrams, bandstructures, and wavefunctions
 Exciton energies and wavefunctions (if exciton model is activated)
MQW Solver Physics
The MQW solver calculates the electronic band structure from the Schroedinger equation based on the 4x4, 6x6, and 8x8 k⋅p method. The gain and spontaneous emission coefficients are then calculated from the carrier density, electronic band structure and wave functions. Excitons, strain and temperature effects can be included. As a 1D solver, the MQW solver assumes the stack is infinite in the transverse directions. A constant carrier density is assumed along each partition of the stack. For a full description of the MQW solver physics, please see MQW Solver Physics.
Supported Materials
The method is mainly suitable for IIIV materials with a zincblende crystal structure. For a list of supported materials in the default database, please see Material Database in Finite Element IDE.
Workflow
The MQW solver can be added to the Finite Element IDE with the MQW button in the toolbar of the Design tab of the Finite Element IDE. The MQW solver GUI can be accessed by rightclicking on the MQW object in the Objects Tree and selecting Edit object to open the Edit MQW Gain Solver window.
The general workflow for using the MQW solver GUI is as follows:
 Create materials for the MQW stack layers
 Set the layers and partitions
 Set the layer strain
 Activate exciton model for electroabsorption modulator simulations (Optional)

Set the physical parameters, including:
 Temperature
 Carrier density
 Bias electric field
 Effective index
 Linewidth broadening
 Valence band offset

Set the simulation parameters, including:
 Frequency range and number of points
 Mesh size
 Transverse wave vector range
 Maximum number of eigenvalues (Advanced)
 Set the boundary conditions (Advanced)
 Run the MQW solver
 Extract results
Instead of starting your simulation from scratch, you can also use one of our Application Gallery examples as a starting point for your simulation:
 For laser simulations: Multiquantum well (MQW) edge emitting laser
 For electroabsorption modulator simulations: GaAsAlGaAs electro absorption modulator
The MQW solver can also be run using script commands. See buildmqwmaterial, mqwgain, and mqwindex for more information.