The thermal phase shifter data collection wizard allows you to automatically generate a thermal phase shifter compact model with Ansys Lumerical CML Compiler™, using simulation files from Ansys Lumerical MODE™ and Ansys Lumerical Multiphysics™.
Required licenses
- Ansys Lumerical MODE™ GUI license
- Ansys Lumerical Multiphysics™ GUI license
- Ansys Lumerical CML Compiler license (For direct export of compiled INTERCONNECT models)
Preparing simulation files
The inputs to this wizard are a Multiphysics (.ldev) simulation file and MODE (.lms) simulation file.
Prior to preparing the files for the wizard, first perform the following analysis using your intended simulation structure:
- Obtain the thermal bandwidth of the phase shifter. You can also use measured values if they are available.
- Extract the thermal tuning efficiency of the target TE and TM modes. You can extract this value by calculating the slope of the real component of the effective index vs. temperature graph.
After completing the analysis above, you can prepare your files for use in the wizard.
There are two methods to extract the data for the thermal phase shifter, either by directly sweeping the thermal power of the heater in the Multiphysics simulation, or by sweeping the voltage of the leads on the heater in the Multiphysics simulation.
Power sweep
The requirements for each simulation file are shown in the subsections below.
Multiphysics simulation file
- A HEAT solver simulation with a completed sweep of the total thermal power of the heater.
MODE simulation file
- The simulation must have eigenmodes successfully solved and all target modes calculated and converged.
- The group index for each mode of interest must be present. You can calculate the group index either through the frequency analysis tab, or through the advanced options inside the eigensolver analysis window for the FDE solver in MODE.
- The HEAT response must be imported using the temperature grid attribute.
- Completed sweep of thermal power, with effective index result defined for each mode of interest. This power sweep must have the same number of points and range as that defined in the Multiphysics simulation file.
Voltage sweep
The requirements for each simulation file are shown in the subsections below.
Multiphysics simulation file
- A HEAT solver simulation with a completed sweep of the voltage defined via voltage boundary condition.
MODE simulation file
- The simulation must have eigenmodes successfully solved and all target modes calculated and converged.
- The group index for each mode of interest must be present. You can calculate the group index either through the frequency analysis tab, or through the advanced options inside the eigensolver analysis window for the FDE solver in MODE.
- The HEAT response must be imported using the temperature grid attribute.
- Completed sweep of applied voltage, with effective index result defined for each mode of interest. This voltage sweep must have the same number of points and range as the voltage sweep defined in boundary condition in the Multiphysics simulation file.
Starting the wizard
The thermal phase shifter data collection wizard package files are attached to this article. The attached files include the main wizard package as well as packages containing examples. Important files are as follows:
- Configuration file: The JSON file in the wizard zip file
/wizard/thermal_ps_wizard/gui_config.jsoncontains default configuration for this wizard. Ensure that thelumapi_pathvariable points to thelumapi.pyfile included with Lumerical products. You can find the default paths here. - Wizard scripts: The folder
/wizard/within the wizard zip file contains all necessary files to run this tool. You can start the wizard by running the python script named main.py under/wizard/thermal_ps_wizard. - Examples: Several example input files are available. For the thermal phase shifter, one power sweep example is attached, and one voltage sweep example is attached.
Wizard Interface
Element, port, and mode settings
The first page of the wizard contains general and mode settings for the generation of the thermal phase shifter model.
Element Info: Enter the description and any notes for the model in this section. You can add multiple notes using the “Add Note” and “Delete Note” buttons.
Ports: Configure location, name and order of the ports on the symbol in this section. Use the default settings to create an element where the input and output ports are centered and are respectively on the left and right side, and the electrical ports are on the top.
QA: Configure the wavelength range used for the phase shifter quality assurance test.
Mode Data: Select the modes of interest for the phase shifter, enter data as follows:
- Mode #: Use the mode number in the “Mode list” of the eigensolver analysis window.
- Mode ID: The numeric ID of each mode, only up to two modes are supported. The ID of each mode can be freely selected but must be consistent across the entire compact model library.
- Name: Name of each mode.
- Loss: Enter additional loss of each mode in this column. The wizard automatically extracts loss from the simulation file. Total loss information is displayed on the final page for confirmation.
- dneff/dT: Enter the thermal tuning efficiency of each mode in this column.
Once you complete the information, press “Next” to enter further information for compact model generation.
Model property and source file settings
The second page of the wizard contains further input parameters for the generation of the thermal phase shifter model such as bandwidth and simulation file settings.
Phase Shifter Data: Enter the bandwidth and resistance of the phase shifter model. When you use voltage sweep in your simulation files, the resistance value is automatically extracted and the value entered here is ignored.
Simulation File: Enter simulation file information as follows:
- Sweep Type: Select either “Power” or “Voltage” sweep type. Ensure your simulation files meets the requirements of the selected type as seen in the section above.
- HEAT: Select the location of the Multiphysics simulation file.
- Sweep Name/Voltage Boundary: When using the “Power” sweep type, enter the name of the power sweep. When using the “Voltage” sweep type, enter the name of the voltage boundary condition for the sweep.
- Parameter Name: Enter the name of the parameter swept in the power sweep in the Multiphysics simulation file. You can find the name of the parameter in the edit window of the parameter sweep. This field is disabled for the “Voltage” sweep type.
- MODE: Select the location of the MODE simulation file.
- Sweep Name: Enter the name of the power sweep for the MODE simulation file.
- MODE Sweep Result Names: Enter the name of the results for the sweeps in the MODE simulation file. You can find the name of the results in the edit window of the parameter sweep.
After entering the required information, press “Next” to extract data from the MODE and Multiphysics simulation files and proceed onto setting up the output.
Output settings
The final page of the wizard contains a confirmation of model information, and settings for the output of the model.
Element information: The scrollable top section of the window contains model information:
- The “General Information”, “Notes”, “Ports”, “Parameters”, “Simulation settings”, and “Phase Shifter Data” subsections contain information you entered on the previous page.
- The “Mode Data” subsection contains information collected from the simulation file and information you entered. Specifically, the “Loss” column displays total loss, which is the sum of the loss you entered, and the loss extracted from the MODE simulation file.
- The “FOM” section contains figures of merit, which are calculated from extracted simulation results. The insertion loss (IL) is calculated via the product of the total loss and the default waveguide length. The thermal power needed for a phase shift, , is calculated from the tuning efficiency and equivalent electrical circuit information. If you wish to enter more accurate values, you can edit the .json file for the model directly, and configure tuning of the model.
Element Name: Enter the desired element name in this field.
Icon: Choose an optional icon (.svg) for the element.
Library Mode: Pick the execution mode of the wizard, the selections are as follows:
- Build INTERCONNECT Model: Generate compiled INTERCONNECT model in the
/wizard/folder of the script. You can import this model into INTERCONNECT by right clicking the “Custom” folder in the Element Library, and use “Redirect” to point to the location of the compiled models. - Add to Existing CML Database: Add extracted information into an existing CML database by selecting a master JSON file. When you select this option, an entry is added to the selected master JSON file, and model JSON files along with the icon (if specified) are added into the
/source/folder of the compact model library. You can then use CML Compiler to compile all models in that library.
Note: When you generate the compact model, numerous model parameters other than those extracted from the simulation file and those specified in the wizard are set to their default values. You can adjust the value of all model parameters prior to compilation by selecting “Add to Existing CML Database” and then modifying the model JSON file in the /source/ folder of the compact model library.
CML Compiler Path: Select the path to your cml-compiler executable file. After you select its path for the first time, the wizard uses the last entry for subsequent runs.
Once you have completed review of the model data and selected the output mode, press “Execute” to complete generation of the compact model.
See Also
Automated model data collection overview
S-parameter (fixed) data collection wizard