Research On The Characteristics Of Fractional Vortex Beam And Experimental Analysis

Fractional vortex has a helical phase structure with zero center intensity and a unique radial notch with a defined Orbital Angular Momentum(OAM).The above features make the fraction Order optical vortex in non-linear optics,biomedicine,optical communications and other fields have a wide range of applications.The main work of the thesis is as follows:(1)The history and the main developments of the vortex beams are reviewed,their main applications and the purpose of the paper are also summarized.(2)The basic theory of integer-order vortex light and several vortex beam generation methods are introduced.The advantages and disadvantages of these methods are compared and analyzed respectively;(3)The theoretical numerical simulation of the light field of the ideal vortex beam with plane wave and spherical wave and the vortex light with Young's double-slit interference.A dove prism was inserted into a Mach-Zehnder interferometer.The magnitude of integer and fractional topological charges was quantitatively measured by using a simple unified formula.(4)The simulation research was conducted on the light intensity distribution and phase distribution with MATLAB.The simulation results showed that the radial gap size was related to the decimal part of topological charge value.To be specific,when the decimal part of topological charge value was closer to half integer,radial gap was more obvious;with the increase of the integer part of topological charge,light spot radius increased.In the paper,a variety of vortex light with of the topological charge being half integer is produced through reflective type of liquid crystal spatial light modulator.The transmission light spot collected by CCD is consistent with the theory simulation results of the paper.