The Study About The Optical Cage With The Hybridly Polarized Vector Beam

With increasing clear of the polarization nature of the optical beam, scalar theorywould not describe the polarization nature of the beam completely, so the concept ofvector beam is proposed. Vector beam is the beam that the polarizing inconsistentbehavior in the cross-section which perpendicular to the propagation direction of thebeam, and this polarization nature can not be fully described by the scalar theory ifthe vector theory is not be used. Tiny particles can be captured and manipulated inthe optical cage which can be generated when the vector beam was strong focused. Itdoes not produce mechanical damage since the beam is the non-mechanical contacton the particle, and it almost has no effect on the ambient of the particles since thedistance between all the mechanical parts and the captured object are much largerthan the scale of the captured object. So the generation of the vector beam in theexperimental and strong focus on the formation of the optical cage have importantapplications in the field of particle manipulation. This paper mainly completed thefollowing work:1. Using of the polarization converter and spatial light modulator (SLM) produce avector beam in the experiment. By adjusting the phase delay angle of the LiquidCrystal Variable Retarder(LCVR) varying from0to continually, the polarizedstate of hybridly polarized vector beams can be changed in real time when thebeam pass through LCVR.2. A new theoretical method of realizing real-time manipulation of the optical cageby changing the hybrid polarization states of a double-ring-shaped hybridlypolarized vector beam is proposed. The intensity distribution of focused thedouble-ring-shaped hybridly polarized vector beams is numerical simulated inthe vicinity of the focal plane by using Richards-Wolf vectorial diffractionmethod. The results show that the optical cage can be formed when the phasedelay angle is zero, and the optical cage can be real-time manipulated when thephase delay angle is not zero. The phase delay angle can be controlled by the external voltage of the LCVR, which we can control the optical cage open orclose in real time by adjusting external voltage.3. By using the Richards-Wolf vector diffraction theory, we investigate thefocusing properties of Bessel-Gaussian radially polarized laser beams modulatedwith a diffractive optical elemen（tDOE）in a4pi focusing system which consistsof two same high numerical aperture lens. The results simulated by Matlab showthat the multifocal spherical spots can be obtained when Bessel-Gaussianradially polarized beam pass through this optical system. The number ofspherical spots is associated with the number of belts of DOE and relative sizeof adjacent ring. The spherical focal spots can move along the optical axis if therelative phase of left and right of the incident beam is changed.4. Prospected the local control amplitude, phase, polarization rotation andellipticity of the beam in the laboratory on the basis of the existing work. TwoSLM are divided into four regions, which change the phase, amplitude,polarization rotation and elliptical polarization degree of the beam respectively.Propose the simple theoretical basis and experimental diagram. This method canbe used to achieve a single point control of the beam when the accuracy is sameas the SLM pixel size.