Design Of A Novel Poincaré Sphere Vector Light Field And Its Focal Plane Control

Our knowledge of the optics continues to increase with the generation of laser and the continuous development of related science and technology.A large number of researchers have turned their eyes to the field of manipulating optical field in order to further explore the potential of laser and the application of the optical field.Among the basic properties of the light,amplitude,frequency,phase and polarization state are important parameters to characterize and manipulate the optical field.By studying vector optical field,researchers manipulate the polarization state in the space domain.Compared with the traditional scalar optical field,there are more degrees of manipulating freedom of the vector optical field.The vector optical fields provide various focal fields,and have many novel properties and application areas.With the increasing interest of vector optical field,it is urgent to develop more kinds of novel vector optical field.The Poincaré sphere is a model that represents polarization state,and each point on the sphere surface represents a type of polarization state.The researchers get the full Poincaré sphere vector optical field by superposing different orthogonally polarized beams.Some new features and applications are obtained,such as flattop beam shaping,polarization state generator,optical trapping and optical communication.This paper focuses on designing and generating a new kind of Poincaré sphere vector optical field,and further study the focal properties.The main contents are as follows:1.This paper proposes a method to construct the Poincaré sphere vector optical field based on 2D flattened Poincaré sphere surface.The Poincaré sphere vector optical field includes the full Poincaré sphere vector optical field and the half Poincaré sphere vector optical field,whose polarization states are from the whole and half Poincaré sphere surface,respectively.We define all the degrees of freedom that can be flexibly modulated in the new vector optical field,and gives the algebraic representation of the polarization state.We theoretically simulate the polarization state distribution and the Stokes parameters of the optical field with various parameters,and analyze the distribution of polarization state of these vector optical fields.2.Based on the experimental method with 4f optical system and spatial light modulator with two-dimensional holographic grating,we generate the new Poincaré sphere vector optical field including the full Poincaré sphere vector optical field and the half Poincaré sphere vector optical field.The experimental results are given according to the parameters of previous simulations,which are in good agreement with the theoretical simulated results.We also summarize the possible causes of errors.3.We study the properties and polarization distribution of the focused Poincaré sphere vector optical field based on Richards-Wolf vector diffraction theory.We cover the Poincarésphere according to the distribution of polarization states in the focal plane,and use the Mollweide projection to achieve two-dimensinal patterns representing the coverage of the Poincaré sphere.We also study to control the coverage rate of the focal field to the Poincarésphere by adjusting the parameters of the incident field.We achieve high-quality full Poincarésphere vector optical field in the focal plane when the proportion of the right-handed polarizations on the wave front satisfies golden ratio.Finally,we analyze the change of spin angular momentum of the optical field in the focusing process based on the two-dimensional patterns showing the coverage of Poincaré sphere intuitively.The spin angular momentum of the half Poincaré sphere vector light field and the full Poincaré sphere vector optical field will annihilate and transform during the focusing process,which may be significant in studying of spin angular momentum of vector optical fields.