Synthesis of an arbitrary elliptical polarization operator

We prove a theorem for transforming the polarization eigenstates of an arbitrary elliptical birefringent device into the eigenstates of another similar device by means of a birefringent device. The theorem is applied to synthesize a specific birefringent device from a circular birefringent device, and a practical setup is described. The resulting birefringence and birefringent axis of the synthesized device can be independently set or modulated. Finally, the theorem is extended to elliptical dichroic devices and elliptical polarizers.