Research On The Tightly Focusing Property Of Vector Beams

There are many important properties of light, and polarization must be one of these properties. The interaction with materials of polarized light has significant application in lots of scopes, such as data storage, optical communication, material processing and biological studies. Generally speaking, light can be divided into light with spatially homogeneous status of polarization and spatially inhomogeneous status of polarization. It is familiar to us that light with linear, circular and elliptical polarization is homogeneous. The in-homogeneous status of polarization depends on the special position in the cross section of propagating beams. In the past researches, we have given much attention to the homogeneous, but because of the unique property and latent value, more and more people pay their attention on the inhomogeneous. Vector beams are of the inhomogeneous, particularly with cylindrical symmetry in polarization, that is cylindrical vector (CV) beams.This thesis describes how to change the fundamental character of the CV beams (the polarization, the amplitude and the phase) to modify the energy density of light field.We introduce the concept of CV beams, their sorts and main feature. The Richards-Wolf vector diffraction integral model is to be introduced, since Huygens-Fresnel principle is not suited to tightly focusing by high-NA focusing leans. And then we give the concept of the apodization function and the integral formula of generalized CV beams.We utilize diffractive optical element (DOE) to partly change the polarization of CV beams, and study the energy density of light field in the vicinity of focus by the numerical analysis. We find that long focal depth and smaller focal spot can be obtained by changing the phase of beams. At last, we succeed to get 1D, 2D and 3D flat-top energy density of light field. By the way, the effect from the apodization function will be discussed.The property of various model CV beams will be studied. Optical cages and optical bubbles can be got around the focus according to the character of radially polarized beams, azimuthally polarized beams and generalized CV beams focused by high-NA lens.