Cloud native EDA tools & pre-optimized hardware platforms
Since its 2018.12 release, OptoDesigner has provided native support for compound components created in OptSim Circuit, which are saved as ‘.moml’ files. A schematic design can be captured in OptSim Circuit and simulated. The same file can then be opened in OptoDesigner, where the familiar OptoDesigner script interface is used to modify the layout. Any modifications are then saved and loaded back into OptSim Circuit.
Non-phase-sensitive waveguide connections between components are stored and accounted for in the simulations as a form of parasitics. The picture below shows a top-down hierarchy where the waveguide connections (with their parasitics) are represented in building blocks at the circuit level (OptSim Circuit), while the image on the bottom shows the schematic representation of those types of waveguide connections between components at the layout level in OptoDesigner.
A component is an entity that has both a schematic and a layout representation, ports, an icon and an actual mask layout. Ports are the connections where information (optical or electrical signals) can enter or exit the component, thereby serving as the physical connection points for waveguides or electrical nets in the layout. Components need to exist on both OptSim Circuit and OptoDesigner sides of the layout. This can either be done natively (by having a separate PDK on both sides) or through the PDAFlow interface, in which case the PDK only needs to be defined on the OptoDesigner side. With the PDAFlow interface OptSim Circuit components will not have advanced models, only the compiled S-matrix models will be available if they are compiled into the PDAFlow PDK.
The first time you load a .moml into OptoDesigner, the autorouter settings will be taken from the PDK, and will not be visible. However, saving and loading the file once from OptoDesigner will make the settings visible and editable.
For more information on autorouter settings, see Autorouting Parameters on our Customer Support Portal (account registration required).
The following steps outline a process for creating a .moml file that works both for OptSim Circuit and OptoDesigner:
In the new compound component, add PDK elements and make connections between the desired ports. Be sure to include the input and output ports as shown below:
2. Right-click in the design area and select Properties ‣ foundryName to set the global properties of the circuit. Set the parameter foundryName to the name of your PDK and choose the pdkName with the correct version. Refer to the corresponding documentation of the PDK for the exact spelling of the name foundry name.
3. Save the .moml file.
If you update the above generated file in OptoDesigner, your OptoDesigner viewer will show a layout similar to the following:
In the viewer, you will see that the output MMIis placed very close to the input MMI, but the autorouter finds a way to create the required connections. If you prefer to change the original placement of the output MMI, you can change the value of the x-coordinate on line 31 from 360 to 800.0, for example. Then click Update to view the changes in the Viewer Window. You will get the following:
To be able to open this .moml file and use it back in OptSim Circuit, you would need to save your changes as in its original format (.moml). But it is recommended to save a separate .spt file to preserve any changes in your script. If you save the changes that you made in OptoDesigner into a .spt file and then save it as .moml, the original positions of your elements in OptSim will not be preserved. This means that, if you save your changes first as a .spt file and then as a .moml file, and you open the .moml file in OptSim circuit, OptSim does not know the original positions of the elements and puts all elements on the same position. The connections however, will be preserved. After modifying the layout in OptoDesigner, you can verify it by opening the .moml file in OptSim Circuit. In OptSim Circuit, you can see the routed elements’ content from the schematic. Right click on the thick red line connecting elements and select the View Route option. A new window will open, showing you series of connections including crossings.
Only simple expressions are allowed as parameters on both the PDK component definitions and on the element usage inside OptSim Circuit. OptSim Circuit and OptoDesigner both have to be able to evaluate the expressions, thus expressions such as mcsGetWidth() are not supported as they only work in OptoDesigner.
If you have any questions please contact us at email@example.com.
The following steps can be taken to help solve common problems in porting designs between OptSim Circuit and OptoDesigner.
1. OptoDesigner does not load the .moml from OptSim Circuit
Problem: You get an error message when you open a moml file in OptoDesigner.
2. Errors opening a .moml from OptoDesigner into OptSim Circuit
Problem: You get error messages when you open a .moml that has been exported from OptoDesigner in OptSim Circuit. Possible causes:
3. When re-opening a .moml in OptSim Circuit, all elements are on top of each other
Problem: You open a moml file that has been exported from OptoDesigner in OptSim circuit. All elements are shown on top of each other, but the connections are preserved. The original locations of the elements are lost. Possible causes: