Computation of the Optical Properties of nano structures

The key challenge we address in this project is to accurately and efficiently compute the effects of unavoidable fabrication disorder on functional 3D nanostructures that trap light for photovoltaic conversion.

Traditionally, optical measurements of real nanophotonic structures are compared to an idealized model. Unfortunately, however, this does not allow to assess the consequences of unavoidable fabrication imperfections, and hampers rational development of efficient solar cells.

Recently, we pioneered X-ray holotomography as a probe of complex 3D nanostructures with 20 nm spatial resolution. When combined with Maxwell computations this provides unprecedented opportunities to study real 3D nanofabricated structures for photovoltaics.

The giant tomography data set of voxels requires, however, important computational innovations: i) the use of polytopic meshes to allow significantly smaller meshes than dictated by the domain’s geometric complexity; ii) the development of discontinuous Galerkin discretizations for the Maxwell equations using polytopic elements; iii) the use of unit-cell Bloch-mode basis functions for robust numerical algorithms that greatly improve the computational efficiency of ultralarge superstructure computations.

Since the software development will be based on the hpGEM discontinuous Galerkin toolkit, our project has spin-off to other applications, including DGEarth for seismics and HamWave for nonlinear water waves.