Focusing Regulation Study On Vector Polarized Beam

As one of the important characteristics of light,Polarization has always been the focus of optical field research.Unlike uniformly polarized beams,vector polarized beam obtains spatially nonuniform polarization.Specially,cylindrical vector beams show potential research values and it's the characteristic solution of maxwell's equations in cylindrical coordinates.The radial polarization and azimuthal polarization are the two typical cylindrical vector polarization and spirally polarized beam is the general form of cylindrical vector polarized beam.If cylindrical vector beam is focused by a high-numerical-aperture objective,a strong longitudinal electric field is obtained.Due to this strong longitudinal component,a small focal pattern can be generated.Adjusting the incident field by introducing a diffractive optical element?DOE?,a intensity distribution fitting certain needs can be obtained.Vector polarized beams has attracted much attention for their unique focusing properties and extensive potential application values,which can be used in particle trapping,particle acceleration,laser micro-machining,super-resolution,and optical storage,et.al.Vector polarized beam is a generalized conception with high value in research and great concern in theory and experiment is still focused on it.The main results and innovations are summarized as follows:1.The research background and status and Debye vector diffraction theory are introduced.Detailed introduction of tight focusing theory of cylindrical vector beams and brief introduction of focusing light manipulation based on diffractive optical element?DOE?are given.2.High-numerical-aperture focusing properties focusing properties of the Bessel-Gaussian beam is studied emphasisly.The influence on focusing intensity distribution induced by different ratios of pupil radius to beam waist and numerical aperture is analyzed.Diffractive optical elements designed by the pupil filtering theory is used to manipulate the focused Bessel-Gaussian beam.3.The focusing properties of the azimuthally polarized laguerre gaussian beams in the focal volume under the modulation of filters is studied.A new type of pupil filter is designed with the benefit of Euler formula and spatial frequency in information optics to manipulate the intensity distribution in the focused volume of azimuthally polarized laguerre gaussian beams.Ultra-long light tube is obtained by MATLAB simulation.4.The focusing properties of two-zone spiral cylindrical vector polarized beam is studied.MATLAB simulation of its strong focusing properties is conducted,and the relation of the focused intensity distribution and the rotation angle?₀???is disussed.By changing the coefficients of rotation angle function,the focused beam can be shaped into a flat-top distribution with a wavelength size.