RETOP: near-to-far-field electromagnetic transformation

RETOP is an open-source Matlab toobox that implements a near-to-far-field transformation for computing radiation diagrams. This transformation is implemented in many electromagnetic software, however for most of them, like COMSOL multiphysics, the transformation is restricted to object surrounded by uniform media (free space). RETOP operates for objects on substrates or buried in stratified media. It can be used to compute the radiation diagram in the superstrate and the substrate . The substrate may support guided modes or surface plasmon modes with metal layers. RETOP additionally computes the in-plane radiation diagram in the guided modes.

Both radiation-diagram computations just need the near-field (computed on a rectangular box that contains the object with any full-wave Maxwell solver). RETOP is especially relevant for calculating the scattering of nanoparticle on substrates. Special attention is made to the interface with COMSOL Multiphysics.