Method and device for polarization-based all-optical switching

This application describes an optical switching method for selectively directing an input beam to at least one of two output channels. The input beam impinges on a polarizing beam splitting surface, splitting the input beam into two beam components of different polarizations propagating along different optical paths. These beam components then pass through a controllable polarization rotating medium which selectively affects the polarization of each of the beam components. The beam components are then directed back onto the polarizing beam splitting surface again, producing at least one output beam which propagates toward at least one selected output channel, depending on the state of the medium. The polarizing beam splitting surface is fabricated on a block of the controllable polarization rotating medium, and the input beam also passes through the medium before being split into two beam components by the polarizing beam splitting surface.