Dielectric geometric phase optical elements from femtosecond direct   laser writing
  We propose to use femtosecond direct laser writing technique to realize dielectric optical elements from photo-resist materials for the generation of structured light from purely geometrical phase transformations. This is illustrated by the fabrication and characterization of spin-to-orbital optical angular momentum couplers generating optical vortices of topological charge from 1 to 20. In addition, the technique is scalable and allows obtaining microscopic to macroscopic flat optics. These results thus demonstrate that direct 3D photopolymerization technology qualifies for the realization of spin-controlled geometric phase optical elements. 
Xuewen Wang, Aleksandr Kuchmizhak, Etienne Brasselet, and Saulius   Juodkazis
physics.optics