Research And Application Of Multi-functional Optically-integrated Metasurfaces

The metasurface is a carefully designed array of artificially arranged subwavelength structures that achieves a unique electromagnetic response by the free modulation of the amplitude,phase,and polarization of light by the meta-units of the metasurface structures,and thus it has a very high information capacity and pixel resolution.Compared with conventional optical components,metasurfaces have great potential for miniaturization and integration of optoelectronic devices due to their thinness,compactness and flexible modulation,which can integrate multiple functions in optoelectronic systems.In recent years,a series of multifunctional novel devices such as metalenses,vector vortex beam generators,polarization converters,and multi-channel multiplexing holography have been realized using metasurfaces to modulate electromagnetic wave fronts.However,current two-dimensional(2D)multiplexing-based metasurfaces have significant limitations in the ability to manipulate various optical parameters and information storage capacity due to space constraints,and have not fully exploited the capabilities of metasurfaces in multitasking applications,while the aspect of three-dimensional(3D)vertically stacked metasurface integrated optics still needs to be expanded and deepened.Therefore,to address these issues,this work carries out research on the design processing and application of multifunctional optical devices based on 3D integrated metasurfaces,and the following research results have been achieved:(1)A novel 3D integrated metasurface is proposed to simultaneously achieve low-crosstalk,polarization-free,efficient full-color holography and high-fidelity micro-imprinting by stacking holographic metasurfaces on a single filter microarray based on a Fabry-Perot(FP)cavity.When the device is irradiated by white light,the color micro-imprinted image can be observed,while under red,green and blue laser irradiation,the full-color holographic image can be projected to the far field by mixing three separate grayscale holograms.This integrated device provides a solution to the bottleneck problem of full-color holography,while still maintaining the functionality of color filters and metasurface holography,improving the versatility of metasurface devices for applications.(2)An integrated metasurface device combining FP-cavity color micro-indentation and dual-channel helicity-multiplexed metasurface holography was designed and prepared.This device imparts optical encryption performance with 2~6-1storage capacity by independently manipulating the amplitude,phase,and polarization of incident light with simultaneous micro-indentation,holography,and spiral modulation dimensions.A specific algorithmic framework was developed to couple holography with structural color,and a particle swarm optimization algorithm was established to optimize the polarization conversion efficiency of the metasurface unit.In addition,the color microprint is processed into a quick response(QR)code pattern,and the sender can edit the encryption key in the QR code online at any time,and the receiver gets the decryption information by scanning this QR code to realize a real-time encryption and decryption scheme.(3)All-optical neural network for multi-information interaction by integrating with complementary metal oxide semiconductor(CMOS)image sensors using polarization-multiplexed metasurfaces.This on-chip integrated device requires only the wave of the amplitude or phase of the object to be recognized as the input signal,and in combination with the polarization properties of the metasurface,enables multitasking interactions at the speed of light in the visible range,such as the simultaneous classification and recognition of digital and fashionable items.Using a machine learning algorithm based on an error back-propagation approach,a dual-channel classifier with a single implicit layer is trained to perform classification recognition of critical dual-class images,and this compact multichannel classifier with integrated CMOS is experimentally prepared and validated.