ESM_File_Fig1 from A tunable electromagnetic metagrating

We explore electromagnetic (EM) wave incidence upon gratings of reconfigurable metamaterial cylinders, which collectively act as a metagrating, to identify their potential as reconfigurable subwavelength surfaces. The metacylinders are created by a closely spaced microstructured array of thin plates that, in the limit of small inter-plate spacing, are described by a semi-analytical continuum model. We build upon metacylinder analysis in water waves, translating this to EM for TE polarization (longitudinal magnetic field) for which the metacylinders exhibit anisotropic scattering; this is exploited for the multiple scattering of light by an infinite metagrating of uniform cylinder radius and angle, for which we retrieve the far-field reflection and transmission spectra for plane-wave incidence. These spectra reveal unusual effects including perfect reflection and a negative Goos–Hänchen shift in the transmitted field, as well as perfect symmetry in the far-field scattering coefficients. The metagrating also hosts Rayleigh–Bloch surface waves whose dispersion is contingent on the uniform cylinder angle, shifting under rotation towards the light-line as the cylinder angle approaches the horizontal. For both plane-wave scattering and the calculation of the array-guided modes, the cylinder angle is the principal variable in determining the wave interaction, and the metagrating is tunable simply through rotation of the constituent metacylinders.

本研究探讨电磁波（EM）对可重构超材料圆柱阵列（作为整体构成的超光栅）的入射情况，以确定其作为可重构亚波长表面的潜在价值。超圆柱体由紧密排列的薄板微结构阵列构成，在板间距离极小的极限条件下，可用半解析连续模型进行描述。基于水波中超圆柱体的分析，本研究将其应用于电磁波（TE极化，纵向磁场），此时超圆柱体表现出各向异性散射；这一特性被用于由均匀圆柱半径和角度构成的无穷大超光栅对光的多重散射，我们从中获取了平面波入射的远场反射和透射光谱。这些光谱揭示了异常效应，包括完美的反射和传输场中负Goos-Hänchen偏移，以及远场散射系数的完美对称性。超光栅还支持Rayleigh-Bloch表面波，其色散依赖于均匀圆柱的角度，当圆柱角度接近水平时，旋转导致其色散向光线方向移动。对于平面波散射和阵列引导模式的计算，圆柱角度是决定波相互作用的主体变量，超光栅可以通过组成超圆柱体的旋转进行调节。