Electro-optical switch for unpolarized optical signals

An improved optical switch of the type including polarizing beam splitter means having first and second faces, for separating an incident light beam of arbitrary polarization into first and second light beams with first and second orthogonal linearly polarized states respectively, said first light beam refracted to propagate along a second path, first reflector means positioned to deflect said second light beam along a path parallel to said first path, and first polarization converter means positioned in said second path for rotating said light beam polarization from said second linearly polarized state to substantially said first linearly polarized state, wherein the improvement comprises:

• (a) first and second electrically responsive path selector means positioned in said parallel paths of said first and second light beams for selecting one of a first plurality of optical paths for said first light beam and one of a second plurality of optical paths for said second light beam,
• (b) a confined layer of electro-optically active liquid crystal means having first and second molecular states, positioned to intercept said first and second light beams in said first polarization state for reflecting said first and second light beams when in said first molecular state, and for permitting light to propagate therethrough when in said second molecular state,
• (c) first and second spaced apart transparent bodies having respective superposed planar surfaces at said liquid crystal layer, said first transparent body being characterized by first and second surfaces parallel to said layer, and by first and second end faces at least one of which is disposed at a predetermined oblique angle with respect to said first or second parallel surfaces, and
• (d) means for selectively aplying an electric field to said liquid crystal means, comprising a plurality of first transparent electrode means affixed to said superposed planar surface of said first transparent body and second superposed transparent electrode means affixed to said superposed planar surface of said second transparent body.

In an optical switch of the type including polarizing beam splitter means having first and second faces, for separating an incident light beam of arbitrary polarization into first and second light beams with first and second orthogonal linearly polarized states respectively, said first light beam refracted to propagate along a first path, and said second light beam refracted to propagate along a second path, first reflector means positioned to deflect said second light beam along a path parallel to said first path, first polarization converter means positioned in said second path for rotating said light beam polarization from said second linearly polarized state to substantialy said first linearly polarized state, the improvement comprising:

• (a) first and second electrically responsive path selector means positioned in said parallel paths of said first and second light beams for selecting one of a second plurality of optical paths for said second light beam, said optical paths selected to define a pair of like-polarized parallel first and second light beams,
• (b) second polarization converter means, positioned for rotating the polarization of said second light beam from said first linearly polarized state to substantially said second linearly polarized state, and
• (c) second reflector means positioned to deflect said second light beam to a path also incident upon first polarizing beam combiner means,
• (d) said first polarizing beam combiner means positioned in said parallel optical paths for combining said first and second light beams to form at least one arbitrarily polarized light beam.

An improved optical switch of the type including polarizing beam splitter means having first and second faces, for separating an incident light beam of arbitrary polarization into first and second light beams with first and second orthogonal linearly polarized states respectively, said first light beam refracted to propagate along a first path, and said second light beam refracted to propagate along a second path, first reflector means positioned to deflect said second light beam along a path parallel to said first path, and first polarization converter means positioned in said second path for rotating said light beam polarization from said second linearly polarized state to substantially said first linearly polarized state, wherein the improvements comprises:

• (a) first and second electrically responsive path selector means positioned in said parallel paths of said first and second light beams for selecting one of a first plurality of optical paths for said first light beam and one of a second plurality of optical paths for said second light beam,
• (b) third or fourth reflector means, positioned to redirect said one of said first and second light beams for said first or second path selector means to third or fourth path selector means, said redirected beams being parallel to and in opposing direction of propagation to said first and second light beams from said first and second path selector means, and
• (c) said first, second, third and fourth path selector means adapted to select at least one of said first or second plurality of optical paths for said first and second light beams and at least one of a third and fourth plurality of optical paths for said first and second redirected light beams, respectively, to emerge as at least one polarized light beam.