Research On Optical Beam Shifts And Spin Splittings Of Reflection And Refraction Of Vortex Structured Light At Interfaces

Refraction and reflection are the most basic optical phenomena and occur in almost all optical systems.Beam shifts(including GH shift and IF shift)and spin splittings in the process of light reflection and refraction have attracted more and more attention by many researchers.The beam shifts and spin splittings of light are very sensitive to the the physical parameters of medium and the change of the state of polarization(SOP)of the incident light.Therefore,they are expected to be used in precision measurement,optical sensing,ultrafast optical analog computing and other fields.On the other hand,Photons are important carriers of information and possess Spin Angular Momentum(SAM),and has spin angular momentum(SAM).The structured light with helical phase-fronts also carries an intrinsic orbital angular momentum(IOAM).The IOAM provides a new physical dimension for manipulating beam shifts and spin splitting.At present,the beam shifts and spin splittings of vortex structured light have become important subjects in spin-orbit photonics.This thesis focuse on beam shifts and spin splittings for vortex structured light at interfaces,and the main research results obtained are as follows:(1)Research on beam shifts of reflected and refracted beams for the vortex structured light impinging on an interface separating two transparent dielectric media with different refractive indexBy analyzing the wave vector-related energy flow(i.e.,|(?)a(?)a|2)of refracted and reflected light field,It is proposed that the wave vector dependent light field coefficient(i.e.,(?)a(?)P/Sa)is the key to study the generation mechanism of beam shifts for vortex structured light reflected and refracted at the interfacethe beam shifts.The expressions of beam shifts of reflected and refracted beams are derived in detail for the vortex structured light impinging on an interface separating two dielectric media with different refractive index.The expressions derived are completely consistent with the expressions obtained by V.G.Fedoseyev and K.Y.Bliokh,et al.,and can be completely self-consistent with the conservation laws(including the law of conservation of momentum and the law of conservation of angular momentum)caused by symmetry in the process of reflection and refraction of vortex structured light,The result of the research is especially helpful for people to deeply understand the mechanism of the beam shifts of the refracted light beam.(2)Research on the beam shifts of the vortex structured light reflected and refracted at the air-anisotropic medium interfaceBased on the combination of angular spectrum method and complex shifts method,the physical source of beam shifts caused by XCI has been thoroughly analyzed.The expresses of the beam shifts for the reflection and refraction of vortex structured light are derived in detail.Simultaneously,the beam shifts caused by XCI was further quantitatively analyzed by introducing a physical parameter NX/Sa(the parameter represents the influence of the XCI on the normalization factor).And the beam shifts caused by XCI can be further manipulated by IOAM.The results of the research solve the important scientific problem of the physical source of the essential difference between beam shifts of the vortex structure light impinging on the air-isotropic medium interface and air-isotropic medium interface,and provide a possible scheme for direct optical measurement of the structure parameters of two-dimensional anisotropic atomic crystal.(3)Research on symmetry and asymmetry spin splitting of vortex structured light at interfacesBased on the combination of angular spectrum method and complex shifts,a mathematical description and generation mechanism of the spin splittings are studied when the vortex structure light with an arbitrary SOP is reflected at an air-anisotropic medium interface.The expressions of spin splittings of the vortex structure light are derived in detail.Then,the symmetrical spin splitting and asymmetric spin splitting are defined by introducing asymmetric spin splitting factor g,and the idea for quantitative analysis of two kinds of spin splitting is given.As the absolute value of g goes to zero,the symmetrical spin splitting occurs,and the total spin splittings can be regarded as the superposition of spin-independent splitting and spin-dependent splitting,and spin-independent longitudinal and transverse splitting are essentially GH shift and IF shift,respectively.As the absolute value of g cannot be ignored compared to 1,the asymmetric spin splitting occurs,and the total spin splitting is viewed as the superposition of an asymmetric spin splitting in the same direction and an asymmetric spin splitting in the opposite direction.The results of this research deepen the understanding of symmetrical and asymmetric spin splitting in the reflection of vortex structural light at the interface.The research results solve some interesting scientific problems in spin-orbit photonics,such as whether the spin splitting for polarized vortex structured light reflected from the interface between air and anisotropic medium is sensitive to the change of the amplitude ratio angle of incident linearly polarized light,and the occurrence condition of symmetrical spin splitting for circularly-polarized vortex structured light reflected at the interface between air and strongly absorbed medium.