Theresearchofthe Generation Anddetectiontechnologyof Vortex Beam Inopticalcommunication

In recent twenty years, cloud computing and big data technology had a rapid development with the growing popularity of communication services and the deepening of social information degree. As a result, the needs for communications capacity in the current information society have reached an unprecedented height. Therefore, in the field of optical communication, dense wave length division multiplexing, orthogonal frequency division multiplexing and mode division multiplexing technology are widely used in in the field of optical communication. However, these are limited by the electromagnetic resources. Since the vortex beam have a new degree of freedom namely orbital angular momentum in addition to intensity, frequency and polarization and the number of orbital angular momentum beam are infinite theoretically, which can substantially increase the capacity of optical communication.For this purpose, the generation and detection technology of vortex beam using for optical communication have attracted more and more people’s attention How to generate the vortex beam with good stability and high fidelity and how to analyze the influence of atmospheric turbulence on the vortex beam detection performance effectively become a key problem. In this paper, we made a deep research on the generation scheme of vortex beam so as to put forward an improved method for sidelobe suppression. What’s more, the detection performance analysis of atmospheric turbulence on the vortex beams has been carried out through numerical simulation. The main contents of this paper are as follows.Firstly, we analyzed thesidelobe problem in the generation of vortex beam. Furthermore based on the generation method using spiral phase plate, we put for ward an improved scheme for suppressing the sidelobe. The simulation results v erified the effectiveness of our scheme; Secondly, after the study of the generation of vortex beam on a single value, we proposed a scheme based on the circular link which can be used for generati ng the vortex beam withtunable orbital angular momentum, this will help to sim plify the system architecture;Thirdly, we analyzed the influence of atmospheric turbulence and the trans mission distance on the detection performance of vortex beam applying for free-space optical communication system. The work will provide a theoretical basis f or the appliance of vortex beam in optical communication;Fourthly, we performed the analysis of thefree space optical communicatio nsystem performancebased on vortex beam with OOK modulation formats. In a ddition, the impact of different initial orbital angular momentum on the SNR per formance is compared. The simulation results show that there exist some orbital angular momentum states can resist the atmospheric turbulence better.