Optical switch employing first and second ferroelectric cells with alignment layers having alignment directions offset by 45°

Claim 1

A ferroelectric liquid-crystal optical switch comprising in succession in the direction of an input optical beam a first crystalline birefringent polarization light separator separating light according to its polarization along a first axis offset from the propagation direction of the input optical beam, a first polarization light modulator comprising a ferroelectric liquid-crystal and having an alignment layer comprising two alignment portions having alignment directions offset by 45° with respect to each other, said alignment portions defining two segments displaced along said first axis to rotate one of the polarization rotations of the beams passing therethrough dependent on the states of the first ferroelectric liquid crystal segments to cause both beams to have the same polarization state, a second crystalline birefringent polarization light separator separating light according to its polarization along a second axis offset from said first axis and said propagation direction, a second polarization light modulator comprising a second ferroelectric liquid-crystal and having an alignment layer comprising two alignment portions having alignment directions offset by 45° with respect to each other, said alignment portions defining two segments displaced along said first axis to rotate one of the polarization rotations of the beams passing therethrough dependent on the state of the second ferroelectric liquid crystal segments to cause the two beams to have orthogonal polarization states, and an exit crystalline birefringent layer having an optical axis parallel with said first direction for recombining the separated light, and further comprising biasing means applied to said alignment portions of said first and second liquid-crystal light modulators for selectively setting the states of said first and second ferroelectric liquid crystals.