Awesome Inverse Design

A curated list for engineers, physicists and hobbyists interested in inverse design of photonic devices.

FDTD Engines

• MEEP - MIT's open-source FDTD engine with adjoint solver, the most widely used in photonics.
• BEAMZ - GPU-accelerated, general FDTD and gradient-based optimization with JAX for photonic chip designers.
• FDTDx - GPU-accelerated, differentiable FDTD with memory-efficient autodiff for 3D inverse design with Jax.
• Tidy3D - Cloud-based FDTD with built-in adjoint optimization and mode solver. (Flexcompute; originated in Fan Group, Stanford)
• fdtdz - GPU-accelerated FDTD in JAX. (SPINS Photonics)
• Khronos.jl - Alec Hammond's new Julia FDTD solver for photonics. (Meta Research)
• Luminescent.jl - GPU + autodiff FDTD in Julia for photonics, acoustics, and RF.

FDFD & Frequency Domain

Fan Group, Stanford:

• Ceviche - Differentiable FDFD and FDTD simulator with autograd for gradient-based inverse design.
• Angler - Frequency-domain electromagnetic simulator with adjoint-based optimization.

Vuckovic Group, Stanford:

• SPINS-B - Gradient-based photonic optimization library using FDFD.

Other Inverse Design & Optimization Tools

• EMopt - Shape and topology optimization for 2D/3D EM structures using the adjoint method.
• PhoTOS - Topology optimization with shape libraries and VAE-based feature mapping for fabrication-aware photonic design.
• NIDN - Neural inverse design of nanostructures with PyTorch, RCWA and FDTD forward models. (ESA)
• lumopt - Adjoint optimization wrapper for Lumerical FDTD.
• PreFab - Deep learning model predicting post-fabrication structures from GDS layouts for fab-aware optimization.

Tutorials & Challenges

• Inverse Design Workshop - Hands-on workshop materials. (Fan Group, Stanford)
• Ceviche Challenges - Suite of photonic inverse design challenge problems. (Google)
• invrs-io Gym - Collection of nanophotonic inverse design challenges with common interface.
• Inverse Design Tutorial (Christiansen & Sigmund, 2021) - Comprehensive tutorial on topology optimization for photonics.
• DTU TopOpt MATLAB Codes - Companion MATLAB/COMSOL code for the Christiansen & Sigmund tutorial.
• Tidy3D Inverse Design Lectures - Free video lecture series on inverse design methods.
• Tidy3D Example Library - Collection of simulation and optimization examples.
• MEEP Adjoint Optimization Notebooks - Jupyter notebooks teaching MEEP's adjoint solver.
• A Newcomer's Guide to DL for Inverse Design (Khaireh-Walieh et al., 2023) - Practical tutorial with companion Python notebooks.
• Validation and Characterization of Algorithms for Photonics Inverse Design (Chen et al., 2024) - Reproducible multi-solver benchmark suite.

Key Papers & Reviews

• Jensen & Sigmund (2011) - "Topology optimization for nano-photonics." Laser Photonics Rev.
• Piggott et al. (2015) - First experimental inverse-designed silicon photonic device. Nature Photonics
• Molesky et al. (2018) - "Inverse design in nanophotonics." Nature Photonics
• Peurifoy et al. (2018) - Neural networks for nanophotonic inverse design. Science Advances
• Hughes et al. (2019) - Forward-mode differentiation of Maxwell's equations. ACS Photonics
• Christiansen & Sigmund (2021) - Tutorial on topology optimization for photonics. JOSA B
• Jiang, Chen & Fan (2021) - DNNs for evaluation and design of photonic devices. Nature Reviews Materials
• Ma et al. (2021) - Deep learning for design of photonic structures. Nature Photonics

Also See

• Awesome Photonics - Comprehensive list of open-source photonics projects.
• Awesome PDA - Papers on photonic design automation.

More tools (less actively maintained or more niche)

• GRCWA - autoGradable RCWA. (Stanford)
• jaxwell - JAX-based FDFD solver. (Vuckovic Group, Stanford)
• fdtd - Python FDTD with PyTorch backend.
• wavetorch - Wave equation backpropagation in PyTorch. (Fan Group)
• pjz - JAX workflow framework on top of fdtdz.
• DL4TO - Deep learning for 3D topology optimization in PyTorch.
• OpenEMS - EC-FDTD electromagnetic solver.
• InverseBench - Benchmarks for diffusion-based scientific inverse problems. (ICLR 2025)
• TMM - Transfer matrix method for thin/thick multilayer film optics.

RCWA & Transfer Matrix

• S4 - Rigorous coupled-wave analysis (RCWA) for layered periodic structures. (Fan Group, Stanford)
• FMMAX - Fourier Modal Method in JAX with Brillouin zone integration. (Meta Research)
• Meent - RCWA with NumPy, JAX, and PyTorch backends for differentiable optimization.
• torcwa - GPU-accelerated RCWA with PyTorch automatic differentiation.
• tmmax - GPU-accelerated transfer matrix method in JAX.

Mode Solvers & Photonic Crystals

• MPB - MIT Photonic-Bands: Bloch-mode solver for photonic band structures in periodic media.
• Legume - Guided-mode expansion for photonic crystal slabs with automatic differentiation. (Fan Group, Stanford)
• femwell - FEM waveguide mode solver for photonics.
• meow - Eigenmode expansion (EME) solver for photonic waveguides.