Optical switches which take multiple incoming optical signals and switch
them to multiple output ports to realize multiple working states. For
example, in a four by four switch embodiment, twenty-four working states
can be selected. These switches rely on magneto-optically or
electro-optically switching the beam polarizations from one state to
another to rapidly change the light path. An optical signal is spatially
split into two polarized beams by a birefringent element. These beams
pass through a series of polarization rotation elements and recombine
into output fibers, achieving polarization independent operation. A
polarization beam splitter may be used as the key element to establish
multi-port switching. Light bending devices that allow two fibers to be
coupled to the light beams using a single lens may be used to achieve
small fiber separation for compactness.