| Artificial microstructures,as a class of nanostructures with sub-wavelength scale,have attracted more and more attention of the scientific community.The physical properties of traditional materials are mainly decided by the molecular or atomic charaters.However,artificial microstructures enable us to manipulate the electromagnetic field with the manufactured giant atoms,which can be utilized to realize novel functions and phenomena.In this study,we proposed a hybrid nanoantenna that can locally manipulate the intensity,spectra,spatial distribution and polarization of the light field.On the other hand,we proposed the quantitive characterization of the artificial microstructures,and further realized the functional design of planar optical devices based on momentum analysis of the optical field.We also proposed dielectric waveguide to realize angle-dispersion-free phase manipulation,and realized Fourier metalens beyond the paraxial regime.We proposed a metasurface that can realize cross-polarization conversion in transmission mode in the terahertz waveband.Taking advantage of the generation of localized surface plasmons,the co-polarization component is suppressed and the crosspolarization component is enhanced.With overall asymmetry,we realized polarization conversion;and with partial symmetry,we improved the bandwidth of the designed metasurface.The polarization converter we proposed could benefit the design of further polarization related planar metadevices.We proposed an analytical method to quantitive the physical propoties of artificial microstructures.With Fourier method utilized to characterize the microstructures in momentum space,we could describe the diffraction field distribution of metasurfaces both in real space and in momentum space.We proposed four guidelines to direct the design of metasurfaces,especially the stable condition,which fulfils the insufficiency of sub-wavelength condition when design a metasurface.We utilized the theory to realize a multifocal metalens,a convex-concave double metalens,a high numerical aperture metalens that can prevent unwanted diffraction orders.The proposed methodology is not limited to metalenses,and can benefit customizable and multifunctional metasurfaces.We proposed high index,large ratio dielectric waveguides that can manipulate optical phase under large field-of-view.The angle-dispersion-free phase is realized based on the initial phase compensation.We utilized the proposed dielectric waveguides to design a Fourier metalens that functions beyond the paraxial regime over a wide bandwith(1100 – 1700 nm).Our Fourier metalens has a compact size,and the actural Fourier transform ability was demonstrated through a diffraction devices.The proposed metalens may exband the applications of micro-optical systems.We proposed anisotropic dielectric microstructures that can carry different optical vortex beams simultaneously.With momentum analysis,we proposed the theory to describe the multifunctional metasurfaces and multi-channel information metasurfaces.We realized simultaneous control of amplitude and phase of optical field with the dielectric microstructures,and realized energy assigned multifunctional metasurfaces.We also studied the chirality of the multifunctional metasurfaces.The design platform we proposed could be easily utilized to achieve other multi-channel metadevices. |
