Comment on "Higher Order Pancharatnam-Berry Phase and the Angular Momentum of Light"

Abstract

In a recent letter, Milione et al. reported the Pancharatnam-Berry phase (PBP) on a higher-order Poincar\'e sphere (HOPS) [Phys. Rev. Lett, 108, 190401 (2012)]. They used two spin-orbit converters (SOCs) to make a trajectory along the HOPS. However, the SOCs actually do not make a path on the HOPS. We briefly discuss a way of acquiring a PBP made by SOCs.