Research On Optical Information Processing Based On Metasurfaces

Optical information processing technology refers to do signal processing by light.It is one of analog information processing,which not requires a computer at all.The signal processing is divided into two major processing methods: processing signal in the space domain or in the time domain.The optical information processing in the space domain is called analog optical computing,and the optical information processing in the time domain is also called all-optical signal processing.Metasurfaces device refers to a planar device composed of discrete sub-wavelength unit structures,which can arbitrarily tune amplitude and phase.The combination of the two technologies has the advantage of compacting the volume and improving the development of integrated devices,especially optical computers.This paper mainly studies the technology of optical information processing in spatial domain combined with metasurfaces,including theoretical research and application.The article mostly researches using metasurfaces to achieve optical differentiation and optical deconvolution computing.The main contents include:(1)Theoretical research on the optical information processing in spatial domain combined with metasurfaces.Firstly,the paper will introduce the two ways of realizing analog optical computing.Then the principle of realizing optical differentiation by one of the methods will be described.Optical differentiation is realized by guide mode resonance,one of the green functions for metasurface.This paper will mainly introduction guide mode resonance and how to realize differentiation through this method.Then the design of differentiation in broadband wavelength will be described.Finally using another method to do optical deconvolution computing will be present.In other words,optical deconvolution computing is done by Fourier transformation.This paper also will introduce the theory of Fourier transformation and the theory of several blocks based on Fourier transformation.All theory build foundation for further design.(2)Research on the realization of optical differential operations by metasurfaces.Firstly,according to the selected method and theory,which is guide mode resonance and working wavelength,the materials of the metasurfaces are selected for research.Secondly,design the parameter of the metasurfaces unit and make a contrast to choosing the best unit cell,completing the design of the whole array and optical differential calculation.Finally,perform the data analysis for the optical differential calculation of the metasurfaces and demonstrate the application of image edge extraction.The first step is to using simulation software to calculate transfer functions.The second step is to calculate imaging edges through these transfer functions,proving the ability of metasurface which can do optical differentiation in broadband wavelength.(3)Research on the use of metasurfaces to realize optical deconvolution computing.According to the content of the theoretical research,Fourier transformation,three blocks are designed.The three blocks refer to two Fourier transform blocks and the transfer function block.The transfer function block is the most important part of the whole design.In other words,the parameter design of the unit cell and the design of the array are most important.And then the data analysis of the optical deconvolution computing is carried out,from one-dimensional to twodimensional information processing,to demonstrate the ability of deconvolution computing.