Generation And Manipulation Of Vector Structured Light Fields

Light field control is one of the most active fields in scientific research today.As an important carrier of information,the effective control of the light field will promote the development of optical information technology.At present,the control of light field is mainly focused on scalar light field,that is,the light field in which the polarization state is uniformly distributed in space.With the further development of science and technology,the limitation of scalar optical field has become more and more obvious.In recent years,researchers have proposed a novel vector structured light field with nonuniform spatial polarization.The research shows that the special spatial polarization distribution of vector light field enables it to form hollow focusing light field,produce extremely strong longitudinal field distribution,and break through the optical diffraction limit.These novel and unique properties have potential applications in particle trapping,optical micromachining,super-resolution,and many other research areas.Nevertheless,the rich polarization characteristics of vector light field have not been fully exploited,and the exploration of vector light field has only taken the first step.In this paper,we will focus on the generation,propagation and manipulation of vector structured light field and the basic physical problems such as the spin-orbit interaction of vector light field.The main research contents are as follows:Firstly,the generation,propagation and diffraction control of cylindrically symmetric vector light field are studied.Specifically,a polarization converter is used experimentally to generate a vector light field with cylindrically symmetrical distribution.The propagation dynamics of vector light field in anisotropic crystals is studied theoretically and experimentally,which can be used to control the diffraction behavior of vector light field.It is found that the spatial diffraction behavior of the vector light field is significantly suppressed or enhanced when propagating in an anisotropic crystal,depending on the parameters of the crystal.In particular,when the anisotropic strength of the crystal is increased sufficiently,the diffraction behavior of the vector light field is completely suppressed,thereby producing a non-diffraction vector field.Secondly,the generation,propagation and dynamic regulation of vector Airy ring light field are studied.In this respect,firstly,we use a spatial light modulator combined with a polarization converter to generate vector Airy ring light field,and study the self-focusing characteristics of this special optical field.Then,the anisotropic crystal is used to realize the dynamic control of the vector Airy ring light field: that is,the self-focusing effect of the vector Airy ring light field can be controlled by the crystal parameters.When the parameters of the crystal change dynamically,the dynamic change of the self-focusing focus can be achieved,which is not achievable for the scalar Airy ring.Thirdly,the spin-orbit separation effect of vector light field is studied.The spin-orbit interaction of light field has always been an important scientific issue.Studying the spin-orbit interaction of light field is conducive to discover novel physical phenomena,such as the spin-Hall effect of light and spin-orbit angular momentum conversion.In this respect,we study the spinorbit interaction of vector light field based on higher-order Poincaré spheres,and observe a new physical phenomenon: spin-orbit separation effect.Specifically,the polarization state of the vector light field begins to undergo adiabatic evolution along the direction of the South Pole or the North Pole at the Poincaré equator,and its inherent spin-orbit separation occurs,producing a certain spin angular momentum distribution,and at the same time,the corresponding geometric phase will be accumulated,which has a helical structure and carries the orbital angular momentum equal to the spin angular momentum.