Manipulating Unidirectional Edge States Via Magnetic Plasmonic Gradient Metasurfaces
Manipulating Unidirectional Edge States Via Magnetic Plasmonic Gradient Metasurfaces
复制标题
通过磁等离激元梯度超表面操纵单向边缘状态
DOI：
10.1007/s11468-016-0361-8
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发表时间：
2017-08-01
期刊：
影响因子：
3
通讯作者：
Liu, Shiyang
中科院分区：
文献类型：
--
作者：
Chen, Huajin;Lu, Wanli;Liu, Shiyang
我们表明，通过设计由铁氧体棒阵列制成的磁等离子体梯度超表面（GMS），可以实现空间传播电磁波与自导向单向边缘态（UESs）的强增强耦合。入射光子在普通周期表面上的转换效率为零，在含有GMS的表面上的转换效率接近80%。其背后的物理原理是，磁等离子体GMS可以通过带折叠或动量补偿效应直接激发边缘态，并将其转化为普通周期表面上的自导向UESs。考虑组成棒在表面上的部分波散射幅值，也可以揭示出UESs的激发，其表现为从外部照明区域的驻波到传播并限制在表面上的自导波的变化，这是UESs的特征。磁等离子体GMS还可用于实现ue的单向相位控制和系统的时间逆对称性破缺特性和入射波的强耦合导致的非互易Goos-Hänchen位移。此外，通过调整梯度或调整外磁场，可以灵活地控制磁等离子体GMS系统的单向特性，大大提高了磁等离子体GMS系统的性能。
We show that a strongly enhanced coupling of spatially propagating electromagnetic waves to self-guiding unidirectional edge states (UESs) can be achieved by engineering a magnetic plasmonic gradient metasurface (GMS) made of an array of ferrite rods. The conversion efficiency of the incident photons into self-guiding UESs exhibits a transition from zero on an ordinary periodic surface to nearly 80 % on a surface incorporating a GMS. The underlying physics lies in that the magnetic plasmonic GMS enables a direct excitation of the edge states due to the band-folding or momentum compensation effect, which are in turn transformed into the self-guiding UESs on the ordinary periodic surface. The excitation of the UESs can also be revealed by considering the partial wave scattering amplitudes of the constituent rods on the surface, which manifests a change from a standing wave in the region subject to an external illumination to a self-guiding wave propagating and confined on the surface, a signature of UESs. The magnetic plasmonic GMS can also be used to implement the unidirectional phase control of the UES and the nonreciprocal Goos-Hänchen shift as a consequence of the time-reversal-symmetry breaking nature of the system and the strong coupling of the incident wave. In addition, the unidirectional features are shown to be flexibly controlled by either tailoring the gradient or tuning the external magnetic field, adding considerably to the performance of the magnetic plasmonic GMS systems.