Separation And Detection Of Orbital Angular Momentum Of Vortex Beam

In recent years,with the continuous development of various mobile communications services,traditional frequency division multiplexing,wavelength division multiplexing,polarization multiplexing and other technologies have been difficult to meet the current development of information technology.The Orbital Angular Momentum(OAM)is theoretically infinite,and there are orthogonality between different OAM states.In the multiplexing communication system,vortex beam with OAM can greatly improve the spectral efficiency,and has become the focus of current research.In this paper,the generation and detection of single-OAM and superposition state are studied systematically.The main work is as follows:1.The holographic diagram loaded into the Spatial Light Modulator(SLM)to prepare vortex beams with different topological charges.The diffraction field distribution of vortex beams with different OAM was theoretically analyzed.2.The interference superposition of two vortex beam phase diagrams was analyzed,the phase diagrams of vortex beams superimposed on different topological charges were simulated,the different superposition vortex beams were generated experimentally,and the distribution law of light field was analyzed.When the topological charge of a vortex beam was known,the topological charge of another vortex beam can be accurately detected,and the topological load of the initial vortex beam is estimated according to the distribution of phase graph.3.The light field distribution of vortex beam with different charge superposition passing after coordinate transformation was analyzed theoretically.The experimental platform was built and the corresponding experimental measurements were completed.The results show that:(1)The vortex beam can be detected according to the central bifurcation number and the external branches number of the phase diagram of the vortex beam superposition state;(2)A superposition of phase images can be used to generate a high purity superposition states of vortex beams.The vortex beams superposition states can be detected by analyzing the diffraction pattern distribution of vortex beams superimposed on different topological charges;(3)The vortical beams with different topological charges are regularly distributed on the abscissa after coordinate transformation,and the separation and detection of the topological charge of the vortex beam can be realized...