Optical Spin Angular Momentum Control Based On Vector Light Fiel

With the development of laser technology and the further study of laser,people’s understanding of laser technology is constantly improving.At present,there are a lot of research results about laser,these research results promote the development of science and the progress of human society,these research results have played an important role in promoting the development of modern human civilization.Due to the importance of laser,scientists can further explore the potential of the laser by adjusting the parameters of laser,thus forming an important research direction-the domain of manipulating the optical fields.Polarization is an important intrinsic property of light.The modulation of spatial variation of laser polarization state to obtain novel vector optical fields have attracted the attention of researchers.Because of the spatially varying polarization state on the wave surface,vector optical fields exhibit many novel properties that ordinary laser optical fields do not have,so it is widely used in quantum information,optical micro-machining,biophotonics,super-resolution microscopic imaging,near-field optics,and other fields.However,the research potential of vector optical fields has not been fully explored,and there are still many noteworthy contents in the area of vector optical fields research.Meanwhile,the spin angular momentum of the photon is related to the polarization of the light,and the spin angular momentum of the circularly polarized light is ±(?).In recent years,much attention has been paid to the manipulation of SAM based on VOFs,which can be used in areas including nanophotonics,quantum communications,quantum optics,and so on.Therefore,the study of spin angular momentum of photon through the vector optical field has become a very valuable research direction.In this paper,two new vector optical fields are proposed theoretically and experimentally for the first time,and the novel effects of spin angular momentum are studied.It provides a new physical basis for the study of the spin angular momentum of photon while enriching the types of vector optical fields,and is expected to be applied in nanometer photonic circuits,optical micromanipulation,and information transmission.The main work contents include the following two aspects:1.Based on the bipolar coordinate,a multi-polar coordinate is designed,and the multi-polar vector optical field is constructed.The multi-polar coordinate is constructed according to the multiple bipolar coordinate system with different rotation angles,and then the multi-polar vector optical field with the change of polarization state in space is constructed according to the multi-polar coordinate,and the detailed generation principle and mathematical description are given.This enriches the types of vector optical fields to a certain extent and provides new ideas for the design of vector optical fields.The multi-polar vector optical field is generated theoretically and experimentally,and it is found that in the case of weak focusing,the spin angular momentum of the optical field occurs the generation and annihilation process of "0-1" and "1-0".This phenomenon is analyzed theoretically,and the corresponding explanation is given in mathematics and physics,which provides a new understanding for studying the focusing behavior of the photon’s spin angular momentum.2.A symmetrically modulated hybridly polarized vector optical field(SM-HP-VOF)is designed based on symmetry.The generation principle and detailed mathematical description of SM-HP-VOF are given,and this optical field is generated experimentally by using a space light modulator and a 4f system.Compared with the conventional hybrid optical field,the spin angular momentum of SM-HP-VOF in the focal field is purely transverse in the case of tight focus,which is not possible in the conventional hybrid field,so the hybrid optical field can be studied more widely.The regulation ability of each parameter on the transverse spin angular momentum of the focal field under tight focusing condition is simulated.The parameters mainly include the number of SM-HP-VOF zones 2N,the topological charge m,and the topological charge l of the segmented vortex phase.The results show that each parameter can regulate the shape,size and symmetry of the transverse spin angular momentum of the focal field to a certain extent.The proposed SM-HP-VOF and its flexible control of the transverse spin angular momentum provide a new way to study the vector field and the transverse spin angular momentum.