ElectromagneticScattering

ONELAB models for 3D scattering problems in nanophotonics.

Quick Install

Open scattererTmatrix.pro with e.g. your precompiled version of ONELAB to compute the T-matrix of an isolated scatterer of arbitrary shape as described in [1].

Synopsis

This project contains ONELAB models for solving various 3D electromagnetic problems on an isolated arbitrary object:

• T-matrix computation [1]
• Quasi-normal modes
• Plane wave response
• Green's function (e.g. to compute the Local Density Of States)

It contains various usefull features in electromag:

• Vector partial waves (AKA vector spherical harmonics)
• Total field formuation with a point source illumination ("an oriented delta")
• Linear eigenvalue problems
• Scattered field formulation
• Spherical PMLs

Installation

The model scattererTmatrix.pro runs with precompiled version of ONELAB.

The model scattering.pro requires GetDP with python support (see install notes below):

• gmsh
• getdp compiled with python support (see below)
• python (>3.5.x) with numpy, scipy and matplotlib

Running the model

Open scattererTmatrix.pro or scattering.pro with Gmsh.

The model scattererTmatrix.pro computes the scattering (T-)matrix solely and does not require any Python support from GetDP. It is quite fast and accurate since it :

• features spherical PML
• features curved elements + high order Webb elements
• re-uses the factorization for each new input harmonic (i.e. one single inversion to get the T-matrix)
• computes the coefficients by integration within GetDP

The default parameters in scattering.pro are also set to compute the T-matrix of a sphere.

Both models retrieve the results from [1].

Authors

Guillaume Demésy and Brian Stout

References

[1] See "Scattering matrix of arbitrarily shaped objects: Combining Finite Elements and Vector Partial Waves" for details about T-matrices.

Installation notes

To enable python support (Python[] function) in GetDP, follow these instructions (with complex arithmetic) and add to the final cmake line:

-DENABLE_PYTHON=ON -DPYTHON_LIBRARY=/path/to/pythonlib -DPYTHON_INCLUDE_DIR=/path/to/pythoninclude

• On Debian/Ubuntu systems, for python3.6 installed with apt-get,
  • /path/to/pythonlib is /usr/lib/x86_64-linux-gnu/libpython3.6m.so
  • /path/to/python/include is /usr/include/python3.6m
• For python versions installed through anaconda in some environment (e.g. env py36 below), a common location is:
  • /somepath/anaconda3/envs/py36/lib/libpython3.6m.so
  • /somepath/anaconda3/envs/py36/include/python3.6m