Double-channel vector spatial light modulator for generation of arbitrary complex vector beams.

We propose an approach for implementation of an arbitrary vector beam based on a vector spatial light modulator (VSLM), which is simply composed by a phase-only spatial light modulator (SLM) and a composed half-wave plate with checkerboard structure. In combination with a four-phase encoding algorithm, the VSLM can transform a linear polarized Gaussian beam or a plane wave into a vector beam with both arbitrary spatial polarization and complex amplitude distributions in two dimensions. It is demonstrated that the VSLM can directly transform pure phase values into two orthogonal polarized complex values with high-diffraction efficiency. Compared with the existing methods for generation of vector beams with SLMs, our approach is on-axis and common-path with simple structure and only involves the zero-order diffraction. The proposed structure is also easier to make an integration and design portable device since it abstains from using optical elements such as special gratings, prisms, and reflectors.