Electrically controllable liquid-crystal rotatable wave plate with variable phase retardation

Liquid-crystal- (LC-) based rotatable wave plates exhibiting phase retardation that is electrically controllable through more than 2pi and rotatable azimuthal orientation of the optical axis have been achieved. One outer surface of the LC cell is coated with a transparent electrode; this controls the phase retardation. A single wave plate of this type is shown to be capable of converting an arbitrary input polarization to any desired polarization, and its applicability to feedback polarization control is demonstrated.