Research On Photonic Assisted Generation Of Microwave Multibeam Based On Spatial Light Modulators

With the rapid increase in communication traffic,various new applications emerge in an endless stream.The fifth-generation mobile communication technology(5G),which is now in the stage of large-scale commercial use,will not be able to satisfy people's concerns about communication quality and data transmission efficiency in the near future.With the increasing demand,the sixth-generation mobile communication technology(6G)has therefore received great attention.Compared with previous generations of mobile communication technology,the sixth generation of mobile communication technology has significant advantages such as high transmission rate,low transmission delay,and high channel capacity.In addition,with the increasing number of users,the demand for communication is also increasing.In order to realize these simultaneous communication functions,and for the simultaneous communication needs of various users,how to realize bidirectional multi-user communication on a super-large-scale antenna array,that is,the generation of microwave simultaneous multi-beam signals is a key issue.The traditional beam forming system is bulky,complex in operation,and small in instantaneous bandwidth.It will gradually no longer be applicable to today's high-end communication technology.However,the emerging optical beam forming technology has the advantages of small size,easy operation,and large instantaneous bandwidth.,Provides a new research direction for array beam generation.This article first introduces the widely used microwave optical multi-beam generation and control methods,and analyzes the principle of the uniform linear array model and the uniform array model of the multi-beam emission,and based on this,three types of multi-emission multi-beams are proposed.The beam generation design method,through the introduction of the design basis,formula derivation,and simulation,the results show that under the conditions of different frequencies and apertures,by adopting different design methods,it is possible to achieve multi-beam generation at a specific angle.In the experimental part,through the joint use of electro-optical modulator and liquid crystal spatial light modulator,a scheme of generating a beam with microwave information and adjustable phase is proposed,and the feasibility of the scheme is verified by combining simulation and experiment.The article first introduces the experimental link flow chart and the principles and parameters of the main instruments.The construction of the experimental link is completed.In one of the optical links,the radio frequency signal is loaded on the optical carrier through electro-optical modulation,and then the signal light is transformed into parallel space light through the collimator;the other way,the local oscillator light is collimated,And then change the phase through the spatial light modulator.The two optical signals pass through the beam combiner in the space to obtain a beam of light,which is received by the photodetector,and the phase frequency curve recorded by the vector network analyzer is used to obtain four sets of phases.The phase values are substituted into matlab for fitting,and finally obtained a beam pointing at angle of 12.8°.