Operation mechanism of electrooptic multimode X-switches

The operation mechanism of electrooptic multimode switches using crossing channel waveguides (X-switch) is investigated theoretically and experimentally. The light propagation through the X-structure as well as the switching behavior of the device is explained in terms of local normal modes. The theoretical model is confirmed by numerical calculations (BPM) and by experiments using Ti:LiNbO3multimode channel waveguides. The results indicate that the generally applied model of total internal reflection (TIR) is not suited to explain the low voltage operation of multimode X-switches.