Generation of rotationally symmetric power-exponent-phase vortex beams based on digital micromirror devices.

Abstract

In this paper, what we believe to be a new method for the generation of rotationally symmetric power-exponent-phase vortex beams (RSPEPVBs) based on digital micromirror devices (DMD) was proposed and demonstrated. Based on the theory of binary amplitude holography and Lee method, the two-dimensional amplitude holograms for the generation of RSPEPVBs were obtained. Then, the experimental setup was established for the generation of RSPEPVBs based on DMD and to verify the phase structure of RSPEPVBs by the Mach-Zehnder interferometer. The experimental results showed that the RSPEPVBs can be generated based on DMD with high beam quality and stability, and the ±1st-order diffracted beams were respectively corresponding to the RSPEPVBs with contrary TCs, which was the first time to report the RSPEPVBs with negative TC. Besides, the overall and ±1st-order diffraction efficiencies of RSPEPVBs generated by DMD were 7.18% and 1.73%, respectively. The method can be applied for the generation of RSPEPVBs with different parameters and quickly achieve mode switching by loading different binary amplitude holograms, which provides a new choice for the generation of new structure beams based on DMD.