超材料的前沿技术研究及应用-元表面：物理与应用.pptx

Metasurfaces: Physics Applications -I ;Backgrounds Periodic/homogeneous metasurfaces Gradient metasurfaces  Metasurfaces for spin-polarized light Conclusions;自由调控电磁(光)波意义重大;;What’s metamaterial?;超构材料（Metamaterials）的定义;超构材料拓展了我们的相图;Metamaterials的奇异性质;I. 奇异的传播波特性;What happens then ? ;体系一定为色散的;怎样制备?; 负折射的实验验证;II. 奇异的表面波特性;特异介质拓展了表面波的相图; 直接导致：完美棱镜、超聚焦;III. Wave Impedance（阻抗）;超构材料给阻抗更大的变化自由度;真实实现;奇异阻抗（反射位相）的应用;;;超构材料 ? 超表面;人工原子 ? “序” ? 应用;Backgrounds Periodic/homogeneous metasurfaces Gradient metasurfaces  Metasurfaces for spin-polarized light Conclusions;Early works on periodic/homogeneous metasurfaces ; (1) Polarization Control: conventional approaches ;28;Experimental realizations;(2) Transmission control ;Ultra-thin transmissive wave-plate;(3) Absorption control;Backgrounds Periodic/homogeneous metasurfaces Gradient metasurfaces:SPP meta-coupler  Metasurfaces for spin-polarized light Conclusions;Start of (gradient) metasurfaces;Our own motivation The arbitrary control of EM wave is a dream for photonic researchers 2 types of EM waves:  Propagating wave (PW) and surface wave (SW);Broad applications of SPPs and spoof SPPs;Controlling PWs or SWs separately;Inherent difficulty Momentum mismatch; Problems with existing PW-SW bridges: (1) Low efficiency!(2) Resonant coupling – working for one angle!;Intuitive physical picture;PW-SW conversion --- finite ideal model;b changes in a super cell to change All other parameters are kept the same Three gradient meta-surfaces are designed with different ξ;Far-field (FF) characterizations;Anomalous reflection at NIR ;Applications: 1) Meta-holograms ;Flat metasurface with parabolic phase distribution Focusing EM waves with very high efficiency Flat, ultra-thin, highly efficient;Issues arising;Near-field (NF) characterizations;Direct proof on the dispersion relation;SW-SPP: Expt FDTD;Has the issue been solved completely?;Decouplings in conventional couplers;Problems of the side-coupler;Our