Generation And Characteristic Of Vortex Beam Array

With the exploration of particle manipulation,people began to pay attention to the array structured light field in order to manipulate multiple particles at the same time to improve the efficiency of particle manipulation.In the array structure light field,the mutual interference of vortex light will produce many characteristics,which improves the degree of freedom for particle manipulation.This thesis takes the mutual interference of vortex light to produce a vortex array light field as a research topic,and studies different forms of vortex light interference.The main research content is divided into three parts.In the first part,we study a kind of equal-amplitude focused vortex light,which produces a multi-circle secondary ring light field outside the common circular ring light field.Using this structured light to perform multi-beam off-axis interference,as the secondary ring continues to diffuse to reach the interference center,the array pattern produced by the interference will continue for a certain distance on the propagation axis without deformation.Next,the power exponential vortex phase is introduced into the equal-amplitude focused vortex light.The rate of change of this special phase increases exponentially in the clockwise or counterclockwise direction,and the light intensity of the propagating vortex light is distributed in a spiral shape.The distance to the interference center at different azimuth angles of the spiral light intensity is different,which introduces a lateral shift for the interference pattern.In the second part,we study the lattice-shaped light field produced by the interference of multiple parallel Laguerre-Gaussian beams.Under the non-coaxial beam interference of three beams,four beams and six beams,at a specific propagation distance,the center of the interference light field will produce a spiral phase,which brings an overall annular energy distribution to the interference pattern.As the topological charge of the incident beam and the number of radial particles change,the annular light field produced by interference will also change uniformly.In addition,at this distance,the interference surface will generate a dot matrix-like jumping light field,so that evenly spaced dot matrix-like patterns appear on the ring.When different numbers of light beams interfere,the dot pattern that appears is not the same.In addition,as the distance between incident beams increases,the lattice light field becomes denser.This provides a convenient control method for multi-particle manipulation.The third part proposes two array vortex generators based on metasurfaces.These two types of generators are formed by etching rectangular holes on the gold film.The first type of generator is formed by a circular arrangement of rectangular holes,and the second type of generator is formed by a rectangular arrangement of rectangular holes.When circularly polarized light is incident,the transmitted fields of the two generators interfere during propagation,forming a densely arranged array of vortex lights.For the annular array vortex generators,the array vortex appears at a few micrometers on the metasurface,while for the rectangular array vortex generators,the array vortex appears at a certain distance from the metasurface and can continue to propagate.In the first and second parts above,this paper studies the principles and characteristics of different vortex lights interfering with each other to form a special array structure light field.In the third part,two metasurface array vortex generators are designed.A densely arranged vortex array is formed in the transmitted field behind the surface.The research has certain application prospects in the fields of particle manipulation and optical communication.