All optical switch

TLDR: In this article, an optical switch for switching first and second input beams linearly polarized in the same direction is presented. But the switch is not considered in this paper, since it is not suitable for the use of a large number of input beams.

Abstract: An optical switch for switching first and second input beams linearly polarized in the same direction. The switch includes a first half wave plate optically coupled to the second input beam, the first half wave plate serving to rotate the polarization of light incident thereto 90 degrees. The switch further includes a first polarizing beam displacer optically coupled to the first input beam and the output of the first half wave plate, the first polarizing beam displacer for refracting the first input beam and the output of the first half wave plate to produce a combined beam, the first input beam and the output of the first half wave plate incident to the first polarizing beam displacer displaced from each other a predetermined distance. The switch further includes a controllable half wave gate having a gate input port, a gate output port, a control input, a passive state and an active state, the controllable half wave gate in the passive state passing the combined beam incident to the gate input port through to the gate output port whereby the polarization of the combined beam is unchanged, the controllable half wave gate in the active state passing the combined beam incident through to the gate input port through to the gate output port whereby the polarization of the combined beam is rotated 90 degrees, a control signal present at the control input causing the controllable half wave gate to switch between the passive and the active states. The switch further includes a second polarization beam displacer optically coupled to the gate output port, the second polarization beam displacer for refracting light incident thereto into first and second refracted output beams displaced from each other a predetermined distance upon exiting the second polarization beam displacer, and a second half wave plate optically coupled to the second refracted output beam, the second half wave plate for rotating the polarization of light incident thereto 90 degrees.