Generation And Manipulation Of Double-ring Perfect Vortex Beam

Vortex beam(VB)is a typical beam with annular intensity distribution and orbital angular momentum(OAM),which has been explored for the applications of optical tweezer and optical communication.However,the radius of traditional vortex beams strongly depends on its values of topological charge,leading to a bottleneck for several applications.Alternatively,perfect vortex beam(PVB),whose radius is independent of topological charges,can enhance the capability of particle capture and rotation.Meanwhile,it can improve the coupling efficiency and prevent the distortion of mode profile,when the PVB is coupled into a ring-core fiber with fixed refractive index profile.Double-ring PVB(DR-PVB)indicates flexible capability of particle manipulation and the capacity enhancement by the implementation of OAM multiplexing.My thesis is focused on the generation and multiple-parameter manipulation of the DR-PVB.The main research outcomes are summarized as follows.(1)We first introduce intensity and phase spatial distribution of various VBs.Then,the concept,the generation and the detection methods of the PVB are summarized.(2)We propose and experimentally demonstrate a DR-PVB generation with full parameter independent manipulation.First,we obtain the computer-generated hologram(CGH)with the complex amplitude modulation(CAM)technique,then load onto the phase-only spatial light modulator(SLM)for the purpose of realizing the CAM,build the experimental setup,and finally verify the successful generation of DR-PVB based on the detection of topological charges.(3)We successfully realize the multiple-parameter manipulation of DR-PVB,including amplitude,ring radius and ring width.Then we carry out a quantitative characterization of the generated DR-PVB with tunable parameters,in terms of both the correlation coefficient and the generation efficiency.After the multiple-parameter manipulations,the correlation coefficients of DR-PVB are above 0.8,together with the highest generation efficiency of44%.Furthermore,we identify that the topological charges of two rings can be independently manipulated basing on the interference pattern between the generated DR-PVB and the Gaussian reference beam.In particular,diversified optical fields such as the hybrid optical bright-ring or dark-ring lattice can be secured.