Research On Vector Vortex Optical Field Array Based On The Control Of Light Field By Multihole Screen

Singular light field,as a kind of structured light,has been a research hotspot in recent years.Among them,phase singularity will produce optical vortex,and polarization singularity will produce vector light field.With the continuous proposal of polarization singular light field generation methods,the application of vector light field in high numerical aperture focusing,particle manipulation,optical information processing,optical communication and other fields has been promoted.Vector vortex light field,which has both spiral propagation of optical vortex and vector state of non-uniform polarization distribution of propagation cross section,has broader application potential.The latest research direction is vector vortex array integrated with multiple vector beams,which can manipulate multiple particles at the same time,carry out multi-channel communication and laser processing at multiple positions.How to generate vector array has always been the focus of research.At present,methods such as Dammann grating,spatial light modulator and super surface have appeared.However,it is hoped that a simpler and more flexible method to generate the light field of vector vortex array will be proposed.Similar to Poincare sphere’s description of polarization state,the researcher proposed a high-order Poincare sphere to describe the vector light field and polarization state.The vector light field at any position on the spherical surface of the high-order Poincare sphere can be generated by superposition of two groups of circularly polarized light as base vectors.Multi-beam interference can produce optical vortex array,and the research of generating vector light field by using porous screen light field regulation has also appeared.On the basis of these studies,we have made a more in-depth study on the method of generating vector vortex array by the regulation of porous screen light field.The research results and innovations are as follows:Firstly,based on Fresnel diffraction,multi-beam interference and superposition principle of vector beams,a method of generating vector beam array by spiral aperture screen is designed in this thesis.Left-handed and right-handed circularly polarized beams are respectively incident on two sets of six-hole screen structures with Archimedes spiral arrangement with opposite rotation directions,and the light fields are superimposed to generate a first-order vector light field array.By changing the position of the spiral pinhole and the intensity of the emergent light,we can modulate the phase difference and amplitude,thus obtaining the vector light field array with polarization state at any position of the high-order Poincare sphere.Firstly,the theory is verified,and some intensity gray maps are extracted for drawing,and the array effect and polarization state distribution are qualitatively analyzed.It is proved theoretically that spiral screen can generate vector vortex array.This method is an extension of vector vortex array generated by multi-beam interference,and provides a new idea for the study of vector light field array.It may be used in optical communication,optical capture,laser processing and other fields.Secondly,an eight-hole screen and a twelve-hole screen which are symmetrically arranged on the circumferences with different radii are designed.By adopting the designed porous screen structure with different topological charges,the higher-order Poincare sphere vector light field array is generated by superposition.At first,we select two sets of four-hole screens and six-hole screens for rotating superposition with different radii,so as to find out that the eight-hole screens and twelve-hole screens arranged on the circumference with different radii can produce second-order and third-order vortex arrays.Then two sets of eight-hole screens are incident with second-order vortices with the same topological charges but opposite signs;Three-order vortices with the same topological charges but opposite signs are incident on two sets of twelve-hole screens,resulting in closed second-order and third-order vector vortex arrays.By adjusting the initial phase difference and amplitude ratio,the polarization state distribution of Poincare sphere at different positions is simulated and analyzed,and various vector distribution States are generated by simulation.No one has used this method to generate second-order and third-order vector polarization States before.