Benjamin
Vial
… nodes · …
I study how electromagnetic and elastic waves behave in structured materials, and I write the open-source codes that compute them.
I build that software for research labs and industry.
What I build for you
Scientific software for research labs and industry: inverse design, custom solvers and multiphysics models.
ConsultingInverse design and topology optimization
Free-form design where every mesh element becomes a design variable. Automatic differentiation gives adjoint gradients of the full physical model, and the optimizer returns layouts you can fabricate. Past work includes microwave cloaks, an illusion device and a bi-focal lens (3D printed and measured), and the doping profile of silicon phase shifters.
Computational electromagnetics
Full-wave simulation of photonic, microwave and RF devices: scattering, gratings and metasurfaces, waveguides and resonators. Quasinormal mode analysis explains how a resonant device works, and chip layouts go from GDS to S-parameters.
Multiphysics and wave modelling
Coupled electromagnetic, thermal, mechanical and carrier transport models at device level. The same methods extend to acoustic and elastic waves, phononic lattices and time-modulated media.
Custom solver development
Tailored finite element solvers in Python, from mesh generation to post-processing. I also package them as binary wheels and conda-forge recipes, so your team installs them with one command (no compiler or MPI setup).
Simulation acceleration
Parallel and GPU execution, reduced models from homogenization and modal expansions, and machine learning surrogates when a design loop needs thousands of evaluations.
Research
Light, sound and vibration in structured media since 2009 (resonances, homogenization and inverse design), at Institut Fresnel, Queen Mary and Imperial College London.
Fig. 1. Metamaterials and MetasurfacesResonant metamaterial absorbers, annular aperture metasurfaces for infrared spectral filtering, and silicon Mie resonators 
Fig. 2. Topology Optimization and Inverse DesignInverse design of photonic, microwave and thermal devices with topology optimization and automatic differentiation 
Fig. 3. Quasi-Normal ModesQuasimodal expansion, perfectly matched layers, mode coupling, isospectral cavities and time-modulated media 
Fig. 4. Elastic and Acoustic WavesQuasinormal modes of thin elastic plates, topological edge states, phononic lattices and sound absorption 
Fig. 5. Homogenization and Effective MediaHigh-frequency homogenization of dispersive media, tunable ferroelectric metamaterials and material parameter extraction 
Fig. 6. Graded-Index Media and InvisibilityScattering-free graded-index media that shape the amplitude and phase of electromagnetic waves, and flat graded-index lenses
Code
The solvers behind the papers, published as open-source Python packages.
- gsimGDSFactory plugin for electromagnetic simulation. Takes a layout from GDS to S-parameters with the Palace (FEM), Meep and GDSFactory FDTD solvers.github.com/gdsfactory/gsim
- gyptisComputational photonics with the finite element method. Solves Maxwell's equations with FEniCS, with ready-made models for scattering, gratings and modal analysis.gitlab.com/gyptis/gyptis
- nannosFourier modal method for multilayer metamaterials. Several FMM formulations, automatic differentiation and GPU acceleration.gitlab.com/nannos/nannos
- protisPlane wave expansion method for photonic crystals, with automatic differentiation and GPU acceleration.gitlab.com/protis/protis
- pytmodSolver for materials with time-modulated properties. Computes scattering and eigenmodes of time-modulated slabs.github.com/benvial/pytmod
- pylattNumerical models of mechanical lattices (truss and frame structures). Computes phononic band diagrams and supports automatic differentiation for metamaterial optimization.gitlab.com/benvial/pylatt
Writing
All posts- Quasinormal modes of Floquet media slabsOur paper bringing quasinormal-mode theory to time-modulated media is out in Physical Review B, with an open-source Python code.
- High-frequency homogenization for dispersive mediaOur article on high-frequency homogenization of periodic media with frequency-dependent materials is out in SIAM Multiscale Modeling & Simulation.
- Metamaterials 2024 invited talkInvited talk on quasinormal modes of thin elastic plates at Metamaterials 2024 in Chania, Crete. Abstract and slides available.
Have a wave problem?
Tell me what you need to simulate, for a research collaboration or a consulting project.