Vector beams generated with a Fourier transform processor with geometric phase grating

Abstract

In this work, we present a method to generate vector beams with a 4f polarization Fourier filtering system that combines a spatial light modulator (SLM) at the input plane and a polarization diffraction grating (PDG) at the output plane. In the Fourier plane, two quarter-wave plates are employed to transform the +1 and −1 diffraction orders onto circular right (RCP) and left (LCP) polarizations, respectively. The PDG at the output plane recombines the two beams producing the colinear superposition of RCP and LCP beams. The application of a random encoding technique to multiplex diffractive elements on the SLM allows the independent encoding of different patterns on the final beam, thus arbitrary vector beams can be generated at the output. Experimental results are included that demonstrate the capability for this approach to encode a variety of polarization vector beams with different topological charges.