Design And Research Of Spiral Phase Plate For Generating Coaxial Composite Optical Vortex

As a special light field with orbital angular momentum(OAM)and phase singularity,optical vortex has important application value in optical communication,particle control and other fields.With the improving of the technical standard,the single vortex cannot completely meet the demand of all kinds of light,the composite optical vortex(COV)composed of multiple vortices came into being.Based on the design of coaxial composite optical vortex generator as the goal,put forward and verified a piral phase plate which can generate coaxial composite optical vortex in this thesis,the main research work is as follows:(1)This thesis introduces the research status of optical vortex and composite optical vortex in recent years,and introduces the basic characteristics,main types,generation methods and main application polarization of optical vortex(2)The simulation model was established and the function of the simulation model was proved by the simulation of the spiral phase plate(SPP).A new kind of SPP called annular spiral phase plate(ASPP)was proposed.By combining SPP with ASPP,a kind of coaxial composite vortex generator is formed,and the ability of generating double-ring and three-ring vortices is verified by simulation model,and the characteristics of double-ring and three-ring vortices are discussed.(3)The spatial light modulator and 3D printer were used to simulate the composite vortex generator,which verified its ability to generate COV.Verified the characteristics of ASPP and the COV generator when generate optcial vortex.(4)The SPP was fabricated by maskless photolithography mechanism,and the photolithography structure with different heights was finally formed through multiple minimum doses of exposure.Finally,the SPP with 5 steps and 4 topological charges was fabricated.The experimental results are verified and several methods to improve the experimental results are put forward.The results show that ASPP can generate optical vortices just like SPP,but it is different in some properties.By combining SPP with ASPP,the coaxial COV can be generated with any number of cycles.The required SPP can also be easily fabricated by maskless photolithography combined with suitable photoresist,which lays a foundation for using photolithography mechanism to generate COV.