The Generation Of Vector Field With The Manipulation Of The Two Eigenstates Of Optical Vortices

Light field regulation is an important research topic in the field of optics.In the space,the conventional regulation methods mainly involving phase and amplitude have been deeply researched and developed,and the polarization rgulation of the light field is becoming one of the current research hotspots.Polarization,as the intrinsic property of light,plays an important role in various fields of optical science and optical engineering.Differing from the scalar beams with spatially homogeneous states of polarization(So P),vector beams with non-separable of polarization and spatial mode have drawn great attention due to its unusual properties.Vector beams have been found important applications in the fields such as tightly focusing,optical trapping and manipulation,super-resolution techniques,optical metrology,and laser materials processing.In addition,vector beams have also potential applications in optical communication and quantum information process.By exploiting both the spin and orbital angular momentum photonic degrees of freedom,the vector beams can be used in dense coding,quantum key distribution(QKD),quantum teleportation,entanglement swapping and multiple degree of freedom quantum memory.Vector light field is a typical representative of phase and polarization regulation,and its broad application prospects have further promoted the development of description ways and generation methods of vector light field.Some distinctive topological geometries are proposed to describe the evolution of both polarization and phase of vector beams,such as higher-order Poincaré(HOP)sphere,hybrid-order Poincaré sphere(Hy PS),making the description of vector beams more intuitionistic and the classification more specific.In the generation method,various specific optical elements have been designed to generate specific vector beams directly,such as subwavelength dielectric gratings,q-plates,digital micro-mirror devices,plasmonic metasurfaces,etc.Additionally,the manipulation of eigenstates of optical vortices in interferometer provides greater convenience for the generation of vector beams.These methods have brought great convenience for generating different vector beams,and have greatly promoted the application and development of vector beams.In this dissertation,based on the manipulation for the eigenstates of optical vortices,the experimental and theoretical research on the generation and regulation of vector light fields are carried out.The research contents of the main chapters are listed as follows:1.In chapter one,we generally describe the four representation methods of polarization state; the common generation methods of optical vortices are introduced;the application and development of the vector light field are introduced;we introduce three common types for describing polarization states of vector light field,including the high-order Poincaré sphere,hybrid Poincaré sphere and generalized Poincaré spheres.2.In chapter two,we mainly introduce the common generation methods of vector light field,including specific methods using dynamic phase,geometric phase,and direct generation in cavity,as well as their advantages and disadvantages;the common optical elements are briefly introduced in the generation of vector field,such as spatial light modulator and q-plate;we simulate the high-order Poincaré beams and hybrid Poincaré beams generated by two-beam coaxial superposition,and other vector light field generated with three-beam coaxial interference.According to the simulation results,we analyze the polarization states,total intensity pattern and polarized component field of the high-order Poincaré field,hybrid Poincaré beams field and other types of vector optical field.3.In chapter three,we design an experimental setup to manipulate eigenstates of optical vortices to generate arbitrary higher-order Poincaré beams,with spiral phase plates(SPP)as the vortex generators.Experimentally,an input plane wave of linear polarization passes through a spiral phase plate(SPP),and it is changed into a vortex beam of certain topological charge with polarization unchanged.It is divided by a polarizing beam splitter into two vortex beams with polarization perpendicular to each other.They are separately operated in the two arms of the Mach-Zehnder interferometer,for the two conjugate TAM eigenstates to be formed and to be modulated.The Dove prism and quarter-wave plates are introduced to make the beams in two arms a pair of the conjugate eigenstate vortices of opposite handedness and opposite topological charge.The phase shift or amplitude ratio between the two eigenstates can be controlled through adjusting the phase compensation plate or half-wave plate,respectively,to generate arbitrary vector beams represented by the point on specific latitude and longitude line of HOP sphere.Two conjugate circularly polarized optical vortices are coaxially superimposed and subjected to Fourier transform,and can be transformed into the cylindrical vector beam with high quality and strong stability.The use of a spiral phase plate makes the generation of vector beams easier,and has the advantages of high efficiency and low cost.This provides more convenience for the research and application of vector beams and is of great significance to related fields.In addition,we simulate the generation of the typical vector beam basing on our experimental system.4.In chapter four,with the designed experimental setup,we experimentally realize arbitrary HOP beams through adjusting the tilted angle of phase compensator plate and the orientation of half-wave plate,and the experimental results are consistent with the simulations.We demonstrate the generation of different kinds of higher-order Poincaré beams,including the beams at points in a latitude or longitude of higher-order Poincaré sphere,Bell states for |l| = 1 and |l| = 2.The radially polarized beams of very high order with l = 16 are generated by cascading the SPP.We numerically analyze the intensity pattern of HOP beams represented by different points on a longitude of HOP sphere,and fit the experimental results with the theoretical formulas.It is proved that the vector beam generator can accurately generate arbitrary HOP beams.Vector beams of high quality and good accuracy are experimentally achieved,and the flexibility,feasibility and high efficiency of the setup are demonstrated by the practical performance.5.In chapter five,we conclude the work in master’s period and introduce the preconceived work in future.