Transmission Modeling And Characteristic Analysis Of Multi-vortex Beams

Vortex beams are intriguing special optical structures with screw wave-front and a phase singularity,which posses phase singularity.It is proved that vortex beams carry the orbital angular momentum(OAM).In addition,encoding data by the OAM of vortex beam is proposed,which may have potential applications in free space optical communication.OAM is a method for realizing multiplexing multiplexing.Recently,using the OAM of light as multiplex channels in MDM system has inspired great interest,due to the orthogonality and theoretically infinite states of the OAM modes.Due to the unique structure,it has attracted much attention of researchers at home and abroad for their application aspects.This kind of special optical field has been applied in many fields that include optical micromanipulation,biomedicine and optics quantum information processing.The main research work includes:(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 stability of the phase singularities of fractional and integral vortex beams during transmission were analyzed theoretically and experimentally.The simulation results show that this method is beneficial to the long distance observation of vortex beam.(3)On the basis of vortex beam,the multi-vortex beams are modeled and the propagation characteristics are studied,the propagation of the light intensity is deduced.(4)The propagation characteristics of double vortex beams which are generated by coaxial superposition of two vortex beams with different topological charge of integer and fractional order are studied theoretically and experimentally.It is found that each ring of the double vortex beam carries different OAM,and is propagating independently.In addition,when the external topological charge of the double vortex beam remain unchanged,the distance between the two rings of the double vortex beam gets smaller with increasing the internal topological charge.The simulation results show that the spotcharacteristics of double-vortex beam can be preserved after propagation,and the orbital angular will not be affected.It shows that the double-vortex beam is stable in the process of transmission and is suitable for free-space optical communication system.