Helicity-dependent forked vortex lens based on photo-patterned liquid crystals.

A liquid crystal forked vortex lens integrated with Pancharatnam-Berry phase is proposed and demonstrated via a dynamic photo-patterning technique. The forked vortex lens can generate two optical vortices with opposite spin and orbital angular momentum, which are spatially separated to two focal points with one optical vortex focused and the other defocused. It exhibits distinctive helicity-dependency and ultra-high diffraction efficiency up to 95%. The topological charges of generated optical vortices are detected via astigmatic transformation. This work supplies an easy fabrication and low power consumption strategy for generating and separating (de-)focused optical vortices simultaneously.