Generation of orthogonal circular polarization with different Berry phase using liquid crystals stacked structure

Abstract

Pancharatnam-Berry (PB) phase devices are attractive as compact flat optics. The PB phase device consists of a nematic liquid crystal (LC) with a pattern alignment. The phase gradient of the output light is given only to a single circular polarization component. In this work, we propose to generate orthogonal circular polarizations with different phase gradients using a stacked LC structure in which a patterned nematic LC is placed on a planer cholesteric LC, and demonstrate its operation via numerical simulations. This structure enables reflective optical elements that can deflect beams with two diffraction orders or generate coaxial optical vortex beams.