Nicolet, André (Institut Fresnel, UMR CNRS 6133, Université Paul Cézanne, Marseille, France)
Zolla, Frédéric (Institut Fresnel, UMR CNRS 6133, Universit´e de Provence, Marseille, France)
The purpose of this paper is to propose an efficient method to compute propagation modes in helicoidal waveguides. An helicoidal system of co-ordinates is introduced to define the structure and to set up the problem. These co-ordinates, albeit non-orthogonal, preserve the translational invariance in a way that allows a two-dimensional finite element model similar to the one of classical straight waveguides.