Research And Design Of Mirrors Of Quasi-optical System Based On Gaussian Beam Modes Analysis Algorithm

In the electromagnetic wave spectrum,the millimeter wave and sub-millimeter wave bands have great research value,and are also relatively new research fields in recent years.With the continuous development of quasi-optical technology,many research methods for quasi-optical systems have been proposed in China or abroad.These methods make the simulation and processing of quasi-optical systems and various parts of devices more and more extensive.Since commonly used methods of quasi-optical system analysis,such as PO(physical optical method)and GO(geometric optical method)used in commercial software GRASP,modeling and analysis of known system parameters are more or less in terms of calculation speed which is lacking.The quasi-optical system analysis method used in this laboratory in the past few years-DGBA(Gaussian beam diffraction analysis method),although it can perform a more accurate analysis of the entire system,but because the DGBA algorithm only considers the basic mode of the Gaussian beam,the lack of suitable control variables to discuss the parameter value of the unknown mirrors.Therefore,in the case where the mirror parameters cannot be known,this paper will introduce an algorithm for studying unknown mirrors-GBMA algorithm(ie,Gaussian beam modes analysis algorithm),and apply this algorithm to the field of designing for quasi-optical system.The Gaussian beam modes analysis method is based on the fundamental theory of quasi-optical,and analyzes the fundamental and higher-order modes of the Gaussian beam.In this paper,a series of derivations are used to convert the Gaussian beam into a high-order mode accumulation form represent the input and output fields of the Gaussian beam.For the unknown mirror parameters of the quasi-optical system,the previous one is canceled by the outgoing cross polarization of the unknown mirror.The output and cross polarization of the mirror can achieve the purpose of determining unknown mirror parameters.Based on the derivation results,the simulation results of GBMA and the commercial software GRASP 10 are compared to verify the accuracy and applicability of the algorithm.At the same time,according to the change trend of the obtained cross polarization isolation,the optimal parameter settings of the system can be obtained.The maximum energy of a quasi-optical system provides a theoretical basis.In order to be more accurate,a quasi-optical system is designed and processed in this paper.The results which tested are compared with the results of GBMA and GRASP 10,which verifies the accuracy of the algorithm.At the end,a quasi-optical modeling platform was built to lay the foundation for applying GBMA algorithm to actual modeling.