Study On Propagation Characteristics And Application Of Vortex Beams

Vortex beam is a kind of bottle beam with spiral wavefront and zero center intensity.Because the phase distribution function of vortex beam contains helical phase factor,it contains the information of orbital angular momentum.The potential application value of vortex beam depends on its unique helical phase structure and unique orbital angular momentum parameters.In this thesis,the propagation characteristics and applications of two kinds of common vortex beams,Laguerre-Gaussian beam and high-order Bessel-Gaussian beam,are studied.Firstly,the propagation characteristics of Laguerre-Gaussian beam and high-order Bessel-Gaussian beam with different parameters are analyzed respectively by numerical simulation.Then,the interference phenomena between two sorts of vortex beams above with the plane wave,the spherical wave are analyzed and researched respectively,and the interference effects of the same sorts of vortex beams with the same opposite topological charges are deeply elucidated.According to the interference pattern,thereby proposing effective and reliable methods for measuring the topological charge value of vortex beam formed in different condition.Finally,being inspired from findings above,the interference superposition of the high-order Laguerre-Gaussian beams with opposite topological charges is studied in depth and applied to the measurement of the polarization rotation angle of the incident beam.Subsequently,the actual efficiencies of two different detection methods are examined and suitable occasion of different methods are explaind.The research results show that the radial index,the topological charges and the propagation distance of the Laguerre-Gaussian beam have a great influence on the intensity and phase distribution of the beam,and the radial index of the wave vector of the high-order Bessel-Gaussian beam influence the propagation characteristics of the beam significantly.The interference pattern of a integer order topological charge Laguerre-Gaussian beam with the plane wave or the spherical wave can be used to measure its topological charge value.Meanwhile,The interference pattern of a positive integer order topological charge Bessel-Gaussian beam with the plane wave can be utilized to measure its topological charge value.Besides,the interference result of a fractional order vortex beam with the plane wave or the spherical wave can be used to judge the range of its topological charge roughly.Meanwhile,interferograms of the same kinds of vortex beams with integer order opposite topological charges can be applied to determine the topological charges accurately,and superposition characteristics of high-order Bessel-Gaussian beams with unequal and opposite sign topological charges can be utilized to estimate the fractional topological charge of a Bessel-Gaussian beams.At last,the interference model of two Laguerre-Gaussian beams with high-order integer topological charges plays an important role in the accurate measurement of the the incident beams' polarization angle rotation.These conclusions have some guidance and they are referential to the application of vortex beams in the fields of medical science,optical communication,optical computation,particle manipulation and so on.