Ultrafast directional switching in photonic-crystal branched waveguides using electro-optical control

We propose and investigate ultrafast switching of light beams between different ports of a multibranch waveguide in photonic crystals. The branched waveguide is made of chains of coupled defects with degenerate states providing guided modes. Introduced at the corner of branches is a control cell made of an electro-optical active material. Depending on the symmetry of the refractive index changes, light propagation can be directed to specified direction. Dynamic changes of refractive index then provide ultrafast switching of light beams into a desired branch.