Directional coupling and branching of optical signals by dark beams

Various types of dark optical beams with respect to their phase dislocation are discussed and their propagation dynamics is analyzed. On the basis of numerical results 1D and 2D optical couplers are proposed. The respective energy efficiencies for each of the output channels are estimated. Multiple charged optical vortices and their topological instability are presented. Through a proper type of perturbation applied to these vortices they could be split into several sub-beams, thus giving the opportunity of proposing all-optical branching schemes. Two output channel distribution schemes for such an optical brancher are discussed.