Design of a three telescope interferometers using a multimode interference waveguide

In order to observe smaller stellar objects, interferometric techniques are used. We propose a new recombiner for three telescopes realised by ion-exchanged on glass (K + /Na + ) using a self-imaging multimode waveguide. The first part of this work consists of a theoretical study. We demonstrate that such a component is feasible even if the guided modes are weakly confined. To achieve this goal, we use three different modelling methods: Finite Difference Beam Propagation Method, Guided Modes Analysis and Radiated Modes Analysis. Each of these methods gives different information and permits to design a recombiner fulfilling the astronomical exigencies. The emphasis is put on excess losses, spatial filtering and polarization dependency. After this demonstration, results obtained with a first component used as a power splitter are presented. We conclude by presenting the remaining work.