Propagation Properties Of Hybridly Polarized Vector Fields In Uniaxial Crystals

With the rapid development of laser technology,the interaction of light and matter has become one of the hot research topics,especially,the emergence of new materials represented with photonic crystals and micro-nano structures has injected new vitality into the research of the interaction between light and matter.As a kind of anisotropic medium,the crystal has a great influence on the propagation properties of the light field.In recent years,because of the special polarization distribution and focal field characteristics,the vector field plays an important role in optical micro-manipulation,single molecule imaging,surface plasmon,laser micro-processing,super-resolution and so on.It is expected to find a lot of new phenomena and effects in the study of the propagation properties of the vector fields in uniaxial crystals.In fact,researchers have begun to study the use of uniaxial crystal to control the intensity distribution and the degree of polarization of the vector field,but the reported investigations only confined to the vector field with localized linear polarization.Based on the the paraxial theory of the optical propagation in uniaxial crystals,the dissertation studies the propagation properties of hybridly polarized vector fields and hybridly polarized vector vortex fields which have complicated polarization states in a uniaxial crystal orthogonal to the optical axis.The contents of this dissertation are as follows:1.We introduce the research background and status of the optical propagation in the uniaxial crystal along the optical axis and orthogonal to the optical axis.Then we briefly introduce the propagation properties of anisotropic crystals,and give paraxial vectorial theory of the beams propagating in uniaxial crystals along the optical axis and orthogonal to the optical axis respectively,which provides a theoretical framework for the study on both hybridly polarized vector fields and hybridly polarized vector vortex fields propagating in uniaxial crystals.2.Based on the paraxial vectorial theory of the optical propagation in an anisotropic uniaxial crystal orthogonal to the optical axis,the propagation properties of the hybridly polarized vector field orthogonal to the optical axis are investigated.The analytical expression of the hybridly polarized vector field in the uniaxial crystal orthogonal to the optical axis is deduced in detail.By the numerical simulation,we study the effect of the anisotropic crystal on the symmetry and polarization properties of the hybridly polarized vector field.The results show that the changes of the beam radius,the propagation distance in the crystal,and the ratio of the extraordinary refractive index to the ordinary refractive index(ne/no)of the hybridly polarized vector field in uniaxial crystals are closely related to the intensity distribution,polarization distribution and spin angular momentum distribution.In addition,the whole distribution of polarization state rotates as the beam travels in the uniaxial crystal along the z axis.This phenomenon is validated by the experimentally measurements.The results show that before and after uniaxial crystal,the whole distribution of polarization state of the vector field rotates a certain angle,which is in agreement with the theoretical predictions.3.Based on the paraxial theory of the optical propagation in an anisotropic uniaxial crystal orthogonal to the optical axis,we also studied the propagation characteristics of the hybridly polarized vector vortex field in the uniaxial crystal orthogonal to the optical axis.Based on the paraxial propagation theory,the expression of the hybridly polarized vector vortex field in the uniaxial crystal is obtained.By the numerical simulations,we study the effect of the beam radius,the propagation distance in the crystal,and the ratio of the extraordinary refractive index to the ordinary refractive index(ne/no)of the hybridly polarized vector vortex field in the uniaxial crystal on the intensity distribution,polarization distribution and spin angular momentum distribution of the light field.In addition,the evolution of the phase distribution of each component under different influence factors is also observed.The results are compared with that of the hybridly polarized vector field in uniaxial crystals.