Optical currents in Poincaré beams

Abstract

Poincar\'e beams are known to host all three types of Stokes vortices (SVs). We present the optical currents (total transverse energy flow or Poynting vector) in Poincar\'e beams that contain a bright SV at the center of the beam. Mainly two types of optical flow patterns are observed: circulation at the center and multiple circulation loops around the center. The circulating optical currents are seen only around ${S}_{12}$ SVs. Open and closed loop-saddle points of the Poynting vector occur in beams containing ${S}_{23}$ SVs at the center. The number of closed loops in the total transverse flow indicates the magnitude of the ${\ensuremath{\sigma}}_{23}$ Stokes index. Experimentally obtained energy flow structures in four different Poincar\'e beams support the theoretical predictions.