The Characteristics Study Of The Generation Of Vortex Beam By Spiral Phase Plate

Vortex beams are new type special of beams, this kind of special laser beam has beenapplied in many fields including optical micromanipulation, laser optics, biomedicine,particle waveguide, optical information processing, molecular optics and atomic optics.Vortex beams has so many characteristics, such as light intensity distributed in a ring,spiral wave front structure, the smaller dark spot size, carrying the determined orbitalangular momentum and so on. The method of generating vortex beam by the spiral phaseplate is concerned and researched widely due to its simple principle, convenient operationand high utilization rate of beams. In this paper, the main research work is as follows:Firstly, outlined search back ground, history, development situation and the applicationprospect of vortex beams. Then, the basic theory of vortex beam is illustrated，as well asanalysis and deduction about the orbital angular momentum based on the theory. Severalmethods of producing the vortex beams are elaborated, pointing out the advantages ofvortex beam produced by the spiral phase plate.Secondly, different kinds of spiral phase plate models are made usingthree-dimensional computer aided design Auto CAD. After that, the model, which isready-made, is imported into the ray tracing software (TracePro) to get vortex beams.Then ordinary transmission and the off-axis transmission characteristics of vortex beamare researched, respectively. At the same time, this paper puts forward a new method usingthe spiral phase plate superposing different topological charge of vortex beams.Finally, it is interference between vortex beam and plane wave, vortex beams andspherical wave that are simulated. Furthermore, vortex beam experiment of young’sdouble-slit experiment is analyzed and simulated using software MATLAB. Subsequently,according to the basic principle of interference, two vortex beams, its topological chargeare equal but symbol are opposite, is simulated. The method of measuring the topologicalcharge of spiral phase plate is proposed.In this thesis, the vortex beam spot broadening, mobile and phase stability duringtransmission is analyted theoretically and simulated by non-sequential ray tracing method. The study found the vortex beams of diffierent kinds of topological charge can be got bythe method of superposing spiral phase plates, which has advantages to getting vortexbeams of high quality in the experiment. In addition, interference characteristics of vortexbeams are researched and methods of measuring spiral phase plate’s topological charge byinterference pattern are proposed, which have theoretical significance for the furtherimplementation of optical micromanipulation.