Generation of helical beams with pre-determined energy distribution based on phase modulation gratings

Abstract

The generation of helical beams with different pre-determined orbital angular momentum states based on computer-generated holograms is studied. The phase-type diffraction gratings are designed by using the Gerchberg-Saxton iterative method，and realized by using the spatial light modulator (SLM). In the experiments diffraction fields with different helical beams distribution are obtained by using the gratings. The theoretical simulation agrees with the experimental results. This method is meaningful for the information transmission based on the orbital angular momentum.