| In the past a few years,circular Airy beams(CABs)have attracted a lot of attention due to their abruptly autofocusing property,which brings about many potential applications in optical micromanipulations.For realizing a stable and easy micromanipulation,optical beams should generate large optical trapping forces,which are related to their intensity gradients.To further enhance the intensity gradient of CABs at the focal plane,introducing optical vortices(OVs)to the beam structures is proposed,which will create hollow intensity profiles at the focal plane to generate stronger optical trapping.Based on this,further modulation of the vortex is added,which can realize the rotating operation of the particles,then we numerically investigate the propagation properties of such ring Airy Gaussian beams(RAGBs).The main achievements of the report are summarized as follows:Firstly,numerical simulations are used to reduce the transmission of RAGBs without OVs in linear medium.The variations of the focus positions and peak intensities of the RAGBs without OVs are studied under different incident light field parameters.Secondly,the transmissions of RAGBs with OVs in linear medium are systematically studied.The effects of parameters such as the number of topological charges,radius and scale factor of the RAGB on the focus position and peak intensity are studied.Finally,by imposing a cosine modulated optical vortex onto a RAGB,we design a CAB with a special beam profile for generating an interesting intensity gradient distribution for optical trapping applications.Then we numerically investigate the propagation properties of RAGBs with CMOVs.The rings of RAGBs with CMOVs will gradually shrink into several main lobes with the increase of the propagation distance.The number of lobes and the peak intensity of each lobe are determined by the factors of cosine modulated function.By designing the initial phase,we can easily change the transversal location of the peak intensity. |
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