Topolopy Optimization Based Research Of Metalens At Endface Of Optical Fiber Bundle

Metalenses are a typical nano optical metasurface device,generally composed of a series of sub-wavelength metal or dielectric units arranged according to the phase requirements of the imaging light field,forming a planar imaging device with diffraction limit resolution;Its ultra-thin,lightweight and easy integration characteristics make it have great advantages in integrating optoelectronic devices.The structure of most metalenses is a discrete nanostructure array arranged on the substrate surface,which requires a large amount of structural geometric data and requires a large number of simulation optimization to find the best structural arrangement,so this design method needs to be improved.Optical fiber bundles have the advantages of small size,high transmittance and low optical loss,but the current imaging systems combined with optical fibers mostly rely on lens groups,which have more components and larger volume,which do not meet the needs of miniaturized imaging systems.The integration of metalens and fiber bundle can fully reflect its thinness and lightness,and the combination of the two is conducive to promoting the miniaturization of imaging systems.In this paper,a novel concentric ring structure metalens is designed by topology optimization method,and numerical simulation experiments are carried out.Electron beam lithography was used to prepare a metalens with a diameter of 720μm and NA of 0.8,and a metalens with a diameter of 30.47μm and NA of 0.8 was prepared by nano 3D printing technology.An imaging optical system integrating metalens and fiber beams was designed,and nano 3D printing was used to complete the integration of metalens and fiber optic image beams.Imaging experiments were carried out using white LED light source,and the results showed that the metalens had good imaging performance.The meta lens and integrated fiber beam imaging system proposed in this paper can be applied to various fields such as medical,industrial,and military.The main content of this article includes the following sections:(1)The research background of metamaterials and metasurfaces is given,which leads to metalenses,and the research status of metalenses and fiber beam imaging technology at home and abroad is investigated,the application fields and development trends of the combination of metalens and fiber bundles are explored,and the research progress is summarized.(2)Introduce the basic theory of metalens,further give the topology optimization method to design the metalens,give the simulation design results of the metalens,the simulation results show that the metalenses have good focusing effect,and the two processing technologies of electron beam lithography and nano 3D printing are used to prepare the metalenses.(3)Analyze the integration problem of metalens and fiber bundle,design the microstructure of the end face of the fiber bundle and complete the overall structure design of the integrated fiber beam imaging optical system,and give the integration method of using nano 3D printing technology to print the metalens on the end face of the fiber bundle.(4)After completing the design of focusing concentric ring topological metalens and the design of imaging optical system integrating metalens and fiber beam,the imaging ability of the metalens and imaging system is verified by imaging experiments,the imaging error is analyzed,and relevant optimization requirements are further put forward for the system.