Diffraction Characteristics Of Optical Vortex Through Different Aperture

Optical vortex is a special annular light field with helical phase structure.Due to its characteristic of orbital angular momentum and special phase structure,optical vortex has important research value in the field of optical micromanipulation and optical communication.Based on the research progress of optical vortex at home and abroad,this paper investigated the diffraction characteristics of optical vortex.Laguerre-Gauss beam(LG beam)is one of the most common optical vortex,and the optical vortex in this paper is LG beam.The main work is as follows:The optical field distribution of LG beam through regular polygonal apertures was researched.The diffraction field distribution and the phase distribution of the LG beams passing through different polygonal apertures are researched by theoretical study,such as the positive triangle,the square and the hexagon.The structural parameters of the diaphragm are modified and the variation of the diffracted light field is analyzed.The spot matrix corresponding to the diffraction aperture will appear with optical vortex passing through a polygon aperture.The number of the spot in the lattice is directly related to the topological charge of the vortex optical phase structure.Moreover,a circular spot appears in the diffraction field when the LG beams pass through the hexagon aperture,which indicates that the number of edges of the polygon is more,the more the diffraction field is closer to the incident vortex light.(2)The diffraction field of LG beam passing through circular apertures was researched.Results show that the intensity of diffracted field is similar to the intensity distribution of Bessel beam through the circular hole and ring aperture,and the phase still retains the structure of LG beam.In addition,the diffraction of LG beam passing through a regular hexagonal circular aperture array was researched.It was found that that change of the number of topological charge can result in a honeycomb,a petal-shaped or a shower-like light field respectively.And with the increase of topological charge number,the diffraction field will appear a pseudo-periodicity variety.The honeycomb light field was analyzed in detail,the influence of the structure of the regular hexagonal circular aperture array on the honeycomb light field is studied.(3)The diffraction experiment of optical vortex is carried out.A forked grating is loaded with a spatial light modulator to produce the optical vortex.The liffraction experiments are carried out with the generated vortex light.The experimental results are consistent with the theoretical results.