Design And Development Of Optical Devices Based On Metasurface

Compared with traditional optical lens,metalens has many advantages such as strong maneuverability to light,flexible design and easy integration.Traditional optics relies on the phase change accumulated gradually in the optical path,and the metasurface based on the generalized Snell’s law can realize arbitrary manipulation of the electromagnetic wave phase,amplitude and polarization,which promotes the rapid development of nano-optics.The dielectric metasurface has the characteristics of high transmittance and high aspect ratio at the sub-wavelength scale,and the PB phase can realize the phase control of the cross-circularly polarized light by rotating the optical axis.It has the advantages of relatively simple cell design and easy device processing.This article mainly studies the theory and design of two mechanisms of metasurface,and explores the processing technology of planar metalens:1.Design of dielectric-based achromatic metalens.The regulation effect of a single unit on the local wavefront of light is explored,and the size relationship of the unit is designed by finite time domain difference(FDTD).Focusing lenses of two wavelengths were designed according to the phase distribution of the lenses,and achromatic lenses of two wavelengths were realized by combination.Through simulation analysis,it is found that the design band has a certain achromatic effect.2.Design of PB phase-based plasma metalens.We conducted a theoretical analysis of PB phase-regulated circularly polarized light,and explored the effect of the rectangular hole size on the conversion efficiency and the relationship between the rectangular hole rotation angle and the PB phase carried by the cross-polarized light.The focusing lens is designed according to the phase distribution of the lens.The simulation calculation based on the FDTD shows that the deviation of the focal length of the metalens from the design value is about 2.5%,and the deviation of the FWHM and the diffraction limit is about 2.7%with good consistency.3.Processing and experimental testing of metasurfaces.Attempts were made on dielectric-based metalens,PB-based plasma metalens,and anomalous reflective metasurface,respectively.Successfully produced PB phase metalens and abnormal reflection type metasurface;completed the experimental test of abnormal reflection type metasurface.The relationship between the reflection angle and the incident angle in the test results is commensurate with the theoretical model.