The Research On Vector Vortex Generation And Topological Charge Measurement

Optical vortex(OV)is one kind of light field with spiral phase structure,which is an important branch of modern singular optics.Dynamics characteristics,orbital angular momentum and spatial phase structure of OV are of important research values in the field of optical image,optical micro-manipulation and communications.In recent years,polarization characteristics of vortex beams have attracted wide attention.Vector optical vortex(VOV)is one kind of anisotropic polarized light,which has the potential application on particle acceleration,single molecular imaging and near-field optics.The generation of optical vortex,transmission of vortex single and measurement of topological charge have been hot areas of research for several years.In this paper,the generation of vector optical vortex and the detection of topological charges are discussed.Pure phase modulation method is used to generate vector optical vortex and perfect vector vortex beam with controllable polarization.Jones matrix is used to describe the electrical field of vector vortex and two holographic gratings are designed based on the pure phase modulation method for modulating x-and y-polarization respectively.By changing the initial phase and topological charge,the polarization state,polarization order and topological charge of VOV could be controlled in any diffraction order.The action was also used to generate the high order perfect VOV.The intensity distribution of VOV with non-integer polarization order and topological charge is discussed.Because of the discontinuous phase distribution the intensity of the VOV has dark area in the ring,which is related to the polarization order and topological charge.The diagonal matrix was used to calculate the intensity distribution and the relationship among intensity,polarization order and topological charge was analyzed.Fan-shape slit diffraction method was used to measure the topological charge and polarization characteristic of VOV was discussed.The topological number and sign could be detected by counting the bright spots number and confirming the position.Dynamic double slit interference was used to measure the topological charge and polarization order.The relationship between double slit angle and intensity was discussed for measuring the topological charge and polarization order.