Design,Fabrication And Spectral Imaging Application Of Reflective Dielectric Metasurface Filters

Spectral imaging technology combines spectral analysis technology and imaging technology.It can obtain spectral fingerprints combining image and spectral information of the object,and realize passive and non-destructive component analysis.At present,the spectral imaging technology is limited by the core optical components,and has the disadvantages of low efficiency,large volume,and cumbersome structure,which greatly limits the application of spectral imaging technology to the development of light platforms in the fields of industrial and agricultural detection,biomedical diagnosis,etc.Compared with traditional optical components,metasurfaces,as a new type of ultra-light,ultra-thin,and ultra-flat optical components,can realize arbitrary regulation of electromagnetic waves in the sub-wavelength size,and have the characteristics of high integration and large degree of freedom in regulation,which is expected to solve the pain points of the development of spectral imaging technology to a light platform.Combining spectral imaging technology with metasurfaces and stacking with image sensors to perform spectral imaging at super-resolution scales and one-time snapshots,giving full play to the advantages of metasurfaces,and achieving high efficiency,miniaturization,and compact spectral imaging systems.Based on this,this paper carried out study of metasurface resonance mechanism and micro-nano processing technology,then proposed a spectral imaging technology based on metasurface,and obtained the following research results:(1)A reflective multilayer guided-mode resonant metasurface that can be regulated by a simple single parameter is proposed.Under the incidence of unpolarized white light,the reflection spectrum with high quality factor is obtained in the visible light band of 400～800 nm,the full width at half maximum of its resonance peak is less than 2 nm,the average spectral reflectance is higher than 90%,and the average background reflectance is lower than 10%.In addition,the designed metasurface has extremely high structural and incident angle robustness,which ensures its ability to achieve efficient filtering in passive devices.(2)For the designed metasurface structure,combined with two sets of micro-nano manufacturing processes: hard mask etching process and conformal filling process,based on three key technologies of electron beam lithography,atomic layer deposition and etching,a set of micro-nano process solutions for embedded structures is proposed.The micro-nano process scheme of the formula structure was adopted,and the effects of atomic layer deposition temperature and etching angle on the metasurface structure were studied in detail.The preparation of the metasurface was completed according to the technological process,and the structure of the metasurface was characterized in multiple dimensions by light microscopy,electron microscopy,atomic force microscopy,etc.(3)Based on the designed reflective metasurface filter,the influence of its reflection principle on the spectral imaging system is analyzed,and an imaging optical path is proposed to realize the spectral imaging of the reflective filter.What’s more,a metasurface array for spectral imaging is designed in detail.Finally,the interpolation algorithm is studied for the system,and various interpolation algorithms and their imaging effects are compared.Spectral imaging simulation is performed with 8 to 16 spectral channels,and the fitting degree with commercial hyperspectral images is as low as 0.0227.According to the metasurface design and processing scheme proposed above,as well as the design and construction of the spectral imaging system,an 8-channel superresolution metasurface filter was prepared,and the spectral imaging picture was obtained by calculating the actual measured spectrum,and the spectrum error and imaging error between the actual image and the simulation were analyzed.