Integrated-optic polarization controller with unlimited transformation range

Abstract

We demonstrate a novel waveguide polarization controller that allows endless transformations from any varying general input polarization state into any varying general output state. The electro-optic controller is implemented in lithium niobate and produces adjustable elliptical birefringence of constant total phase retardation via three independent drive voltages. We show that it allows fast and reset-free automatic polarization control using an entirely analog feedback circuit that derives its error signal from the intensity in the prescribed output polarization.