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Properties
General tab
CALCULATE COLD CAVITY SPECTRUM: Specifies whether optical only, “cold cavity” simulation is performed, or fully coupled simulation is performed.
CHARGE TRANSPORT SOLVER: Specify the charge transport solver to be used in fully-coupled simulations.
GAIN SOLVER: Specify the optical gain solver to be used in fully-coupled simulations.
REFLECTIVITY STRUCTURE GROUP: Specify the structure group to use for reflectivity estimation calculations. For more information on reflectivity estimation, see section below on Reflectivity tab. For the structure group selected (or all structure groups, when “all” is used), ensure that all objects in the geometry are adjacent to each other, and that there are no void, i.e., undefined or background material without their own geometry object, within the selected group. If a void is present, the stackrt calculation will result in an error.
Optical tab
The Optical tab contains four sub-tabs used to adjust options for the optical cavity solver.
General
SIMULATION REGION: Specify the simulation region of the optical cavity solver. This can be different than the CHARGE simulation region
CYLINDRICAL AXIS: Specify the cylindrical symmetry axis in the simulation domain, e.g., if x-min is selected, the boundary with the smallest x-value will be used as the symmetry axis, and the simulation domain is wrapped as a cylinder around that axis.
Mesh
Global Mesh Constraints
EDGES PER WAVELENGTH: Specify minimum number of edges per wavelength used in the mesh.
REFINE BASED ON MATERIAL PROPERTIES: When checked, the effective wavelength in the material (\(\lambda/n\)) is used. Otherwise, the wavelength in vacuum is used for all material regions.
POLYNOMIAL ORDER: Specify the order of the basis function used in the finite element solver. A higher order function allows for better resolution even with a coarser mesh.
Under Advanced Options
TRIANGLE QUALITY: Specify the quality of the mesh triangle. The quality is related to the minimum angle in a triangular mesh cell. The higher the quality, the higher the minimum allowed angle.
OVERRIDE DEFLECTION TOLERANCE: Enable to adjust the deflection tolerance from its default value.
DEFLECTION TOLERANCE: Controls how curved surfaces are broken up into multiple linear segments. A smaller deflection tolerance forces the geometry builder to break up a curved surface into smaller segments.
Modal Analysis
SWEEP TYPE:
- SINGLE: Single frequency.
- LINSPACE: Sweep frequency linearly – only available if the option “with source” is selected.
WAVELENGTH and FREQUENCY: Specify either the wavelength or frequency of the mode.
NUMBER OF POINTS: Number of points in the sweep.
FREQUENCY/WAVELENGTH: Specify the center wavelength or frequency. This option only appears if “SINGLE” is selected for “SWEEP TYPE”
WAVELENGTH MIN (um)/WAVELENGTH MAX (um): Specify the minimum and maximum wavelength in micrometers for a linearly spaced sweep. This option only appears if “LINSPACE” is selected for “SWEEP TYPE”
NUMBER OF TRIAL MODES: Specify the number of optical frequencies (k-indices, indicating eigen values) to consider in the optical cavity equation. This option is disabled and will not be used if a dipole source is used.
Laser Cavity Options
NUMBER OF FOURIER COMPONENTS: Specify the number of Fourier components (m-indices) in the cylindrical cavity to be included in the solution to the optical cavity equation.
MAX NUMBER OF LASING MODES: Number of modes used in fully coupled simulations. If only a cold cavity (optical only) is simulated, this option is ignored. Each mode is uniquely specified by its optical frequency (k-index) and Fourier component (m-index).
WITH SOURCE: If enabled, solves the laser cavity equation with a dipole source, with the specification of the source controlled by the “dipole orientation” and “dipole position” below.
DIPOLE ORIENTATION: Specifies the orientation of the dipole source using a triplet of cartesian coordinates, only applies if “with source” is enabled.
DIPOLE POSITION (um): Specifies the position of the dipole source in micrometers using a triplet of cartesian coordinates, only applies if “with source” is enabled.
Advanced
Global Solver Controls
MULTITHREADING: If enabled, the user can choose to divide up and run the simulation over multiple threads.
AUTO REMOVE PML MODES: If enabled, unphysical modes that have their energy primarily in the PML layers are removed and discarded.
THRESHOLD FOR PML MODE REMOVAL: When “AUTO REMOVE PML MODES” is on, modes are discarded if the fraction of the energy in the PML is larger than this threshold.
Reflectivity tab
Provides an analytical estimation of the transmission and reflection of the cavity based on the cavity multilayer structure and the STACK solver. Results from this estimation can be used to find the resonance frequency of the cavity, to be used in the modal solutions.
In the General tab, the structure group used for reflectivity estimation should be set.
Upon partition, the table in this tab will be automatically populated based on the selected structure group. The reflectivity estimations using the stackrt function, as a function of incident angle and frequency/wavelength is returned as a dataset attached to the VCSEL solver object.
Options
Incidence Angle
MIN (DEGREE): Minimum incident angle (from the normal vector of the surface) of the plane wave.
MAX (DEGREE): Maximum incident angle (from the normal vector of the surface) of plane wave. For single angle analysis, set the angle to the same as the minimum.
NUMBER OF POINTS: Number of points in incident angle sweep.
Frequency/Wavelength
FREQUENCY/WAVELENGTH: Whether to use frequency or wavelength to specify the plane wave.
MIN: Minimum frequency or wavelength in sweep. The default unit for frequency is THz, and the default unit for wavelength is microns.
MAX: Maximum frequency or wavelength in sweep. The default unit for frequency is THz, and the default unit for wavelength is microns.
NUMBER OF POINTS: Number of points in frequency or wavelength sweep.
Advanced tab
Update Limiting
PHOTON RATE EQUATION MAX UPDATE (PHOTON NUMBER): Limit the maximum update of photon number to prevent the simulation from diverging.
Note: Other convergence options can be found in the “Advanced” tab of the CHARGE simulation solver object.
Results Returned
stack_reflection_transmission_coefficients
This result is available upon partitioning the simulation region. Results from stackrt calculations, configured from the Reflectivity tab is shown in this dataset. For more information on stackrt, see the Knowledge Base article on the stackrt command.
Attribute |
Description |
---|---|
rs | Complex reflection coefficient for s-polarized wave. |
rp | Complex reflection coefficient for p-polarized wave. |
ts | Complex transmission coefficient for s-polarized wave. |
tp | Complex transmission coefficient for p-polarized wave. |
Rs | Fraction of reflected power for s-polarized wave. |
Rp | Fraction of reflected power for p-polarized wave. |
Ts | Fraction of transmitted power for s-polarized wave. |
Tp | Fraction of transmitted power for p-polarized wave. |
Frequency/Lambda | Swept frequency range (Hz) or Lambda (m) as set in the Reflectivity tab. |
Theta | Swept angle of incidence as set in the Reflectivity tab. |
grid
Stores information on the finite element mesh. If “polynomial order” (in the Mesh tab) is set to a value greater than one, the actual mesh in results will be more refined compared to the one shown here. For example, if “polynomial order” is set to two, each mesh edge shown in this mesh will be subdivided into two segments.
Attribute |
Description |
---|---|
ID | Domain ID. |
area | Element area. |
index | Optical index. |
fields
Contains field properties for each mode, characterized by the mode number representing different optical frequencies (k-index), and Fourier component index (m-index). Note that while cartesian notation is used here, they are mapped to the cylindrical coordinate system. See the Knowledge Base article on Coordinate Mapping for more details on how the cartesian coordinates are used to represent the cylindrical system.
Attribute |
Description |
---|---|
Electric | Electric field. |
Energy | Electromagnetic energy. |
Magnetic | Magnetic field. |
Poynting | Poynting vector. |
Mode Number | Mode number corresponding to an optical frequency. (k-index) |
Rotational Fourier Index | Fourier component index corresponding to a spatial profile in the cavity. (m-index) |
mode properties
Additional mode properties for each combination of mode number and Fourier component in the “fields” dataset is shown here. The mode number and Fourier component is the same as those in the “fields” dataset.
Attribute |
Description |
---|---|
Frequency | Optical frequency of mode (Hz). |
Power | Mode power in the cavity (a.u.). |
Mode Number | Mode number corresponding to an optical frequency. (k-index) |
Rotational Fourier Index | Fourier component index corresponding to a spatial profile in the cavity. (m-index) |
See Also