Introduction to photonic inverse design with lumopt2#

Inverse design is a computational design approach in which the desired functionality of a component or system is specified first, and optimization algorithms are then used to determine the structure or parameters that best produce that response. Unlike traditional design workflows, which rely on iteratively adjusting a limited set of parameters and evaluating candidate geometries, inverse design enables systematic exploration of much larger design spaces. This makes it especially valuable for complex photonic designs, where brute-force parameter sweeps become increasingly costly and less effective as the number of parameters grows.

The Ansys Lumerical solution for photonic inverse design, lumopt2, is named after the Python module of the same name included in the Ansys Lumerical installation. The lumopt2 module provides a simple and intuitive Python interface for configuring and running inverse design optimizations with Ansys Lumerical FDTD.

In just a few steps, you can define an optimization session with your custom parametrization and figure of merit, run the optimization, and analyze the results.

Installation#

The lumopt2 module is included with the Ansys Lumerical products and requires an existing Ansys Lumerical installation.

Using PyLumerical#

PyLumerical is set up such that if there it detects a Lumerical installation with the module, you can directly import lumopt2.

To use lumopt2, first create a Python virtual environment and install PyLumerical.

1python -m venv .venv
2source .venv/bin/activate
3python -m pip install -U pip
4python -m pip install ansys-lumerical-core

1python -m venv .venv
2.venv\\Scripts\\activate.bat
3python -m pip install -U pip
4python -m pip install ansys-lumerical-core

1python -m venv .venv
2.venv\\Scripts\\Activate.ps1
3python -m pip install -U pip
4python -m pip install ansys-lumerical-core

Then, import the lumopt2 module and it is ready to use.

1import ansys.lumerical.core.lumopt2 as lmpt

Warning

  • To ensure correct functionality, only import lumopt2 through ansys.lumerical.core.

  • Manual sys.path overrides for lumopt2 are unsupported. The lumopt2 module bundled with Ansys Lumerical products silently takes precedence over those added to sys.path.

Using the in-product script editor#

You can also use lumopt2 in Python scripts run from the Script Editor in Lumerical products. Import the module with a single line:

1import lumopt2 as lmpt

Note

The import syntax between PyLumerical and the in-product script editor slightly differs, as the in-product script editor uses a bundled Python environment.

Getting started#

Follow the example below to quick get started with basic functionalities of lumopt2.

Simple metalens

Learn the basics of lumopt2 through a simple example of a metalens optimization.

Getting started with lumopt2: simple metalens

Follow these examples for more in-depth introductions catered to specific workflows.

L-bend

Learn how to optimize components for integrated photonic circuits through a simple L-bend example.

Getting started with lumopt2: L-bend

Workflow#

The diagram below illustrates the general workflow for using lumopt2. For further information, click on the corresponding card.

Optimization session

Configure your optimization using your project definition, along with additional optimizer and callback settings.

Optimization session in lumopt2
Run optimization
Running the optimization
Optimization results
Optimization results
Project
Base simulation

Define the base FDTD simulation for optimization.

Base simulation
Parametrization

Define the map between optimization and structure parameters.

Parametrization
Figure of merit

Define the objective function based on specific simulation results.

Figure of merit