Two-dimensional polarization rotator using a twisted-nematic liquid-crystal display

We present a novel configuration for a twisted-nematic liquid-crystal display (TN-LCD) that makes it operate as a controllable polarization rotator. We extend a previously reported polarization rotator configuration using a zero-twist LCD inserted between two quarter-wave plates. We first operate the TN-LCD in the polarization eigenvector configuration and show how this system can act as an equivalent voltage-controlled wave plate. Next we incorporate this wave plate into the optical rotator configuration. We show that the plane of polarization of the transmitted light can be rotated as a function of the phase introduced by the display. Finally, we create a 2D polarization mask where different areas of the TN-LCD form different polarization states. Experimental results are included.