Research On Optical Metasurface Light Field Phase Control And Beam Manipulation Devices

In recent years,photonic integration and optical chips have become a research hotspot in modern photonics.In the face of the increasingly stringent integration requirements in modern photonics systems,more miniaturized optical devices are urgently needed to control electromagnetic waves.As a new type of two-dimensional artificial material,the size of metasurface is much smaller than the working wavelength,and the metasurface can flexibly control the basic physical properties such as phase,amplitude and polarization state of electromagnetic waves.The realization of phase control is a very important application of metasurface.Metasurface based on phase control have been applied in many aspects,But there are still some problems to be solved in these works.For example,the theoretical system of metasurface phase control is not perfect,and the function of optical devices based on phase control metasurface design is relatively single.Based on the above problems,this paper has carried out research on the principle of metasurface phase control and beam manipulation devices.Our specific work is as follows:(1)Based on the transmission phase metasurface,a design idea of multi-channel polarization beam splitter is proposed.Firstly,the phase response and transmission efficiency of metasurface unit structure to xpolarized light and y-polarized light under different geometric parameters are numerically simulated,and nine unit structures with high transmission and certain phase relationship are selected to construct polarization beam splitter.After that,using the selected nine nano-antennas through different permutations and combinations in the optical communication band with a wavelength of 850 nm,the symmetric dual-beam splitting,asymmetric dual-beam splitting,triple-beam splitting and quad-beam splitting of 45°linearly polarized light can be efficiently realized.The first-order diffraction efficiency of each polarization beam splitter exceeds 88%.When only the x polarization component or only the y polarization component,the four-channel beam splitter we designed can efficiently achieve dual-beam splitting of two polarized light and the transmittance reaches 96%,and the first-order diffraction efficiency exceeds 90%.Compared with the previous design of the beam splitter,the design of the beam splitter provides a higher degree of freedom is no longer limited to the previous beam splitter simple dual-beam splitting effect makes it have a wider range of application scenarios.(2)Based on the all-dielectric huygens metasurface,the design of single-focus metalens and multi-focus metalens is realized in the nearinfrared band.Huygens metasurface is mainly based on the superposition of electric dipole resonance and magnetic dipole resonance to achieve transmission enhancement and phase mutation of 2π to achieve wavefront manipulation.According to this characteristic,we design singlefocus coaxial metalens,single-focus off-axis metalens,dual-focus metalens and quad-focus metalens in the near-infrared band by using the hologram method of Fresnel diffraction principle.The designed metalens can achieve high transmittance and diffraction limit focusing in the nearinfrared band.At the same time,we can also design a focusing metalens with any number of focal points according to different application scenarios.The nanoantenna height of the huygens metasurface is low,making it easier to prepare.