Generation and optimization method of vortex beam array based on phase sinusoidal grating
Firstly,the diffraction field distribution of a two-dimensional sinusoidal grating is derived through theo-retical deduction,and based on the Fraunhofer diffraction theory,the expression of the field distribution in the target plane for a Laguerre-Gaussian beam passing through the grating is obtained.The numerical simulation results show that when a Laguerre-Gaussian beam passes through a two-dimensional phase sinusoidal grating generated by orthogo-nal overlapping of two one-dimensional gratings with same frequency and period,an N∗N array of vortex beams con-sisting of the same topological charge is generated at the target plane.However,the intensities of vortex beams with different diffraction orders are unequal.To overcome this drawback,the grating is optimized using the Simulated An-nealing algorithm.A 3∗3 array with optical intensity inhomogeneity of 0.11‱ and diffraction efficiency of 81%,a 4∗4 array with optical intensity inhomogeneity of 0.03‱ and diffraction efficiency of 72%,and a 5∗5 array with op-tical intensity inhomogeneity of 5%and diffraction efficiency of 71%are obtained.The results demonstrate the simplic-ity and practicality of this method for generating vortex beam array,which will provide technical support for the appli-cation of vortex beam array with the same topological charge.
NETL
NSTL
万方数据
