Department of Optics and Quantum Electronics, University of Szeged, Dóm tér 9, Szeged, 6720, Hungary.
Department of Computational Optimization, University of Szeged, Árpád tér 2, Szeged, 6720, Hungary.
Sci Rep. 2023 Mar 22;13(1):4701. doi: 10.1038/s41598-023-31685-7.
Single and multiple layers of sub-wavelength periodic Babinet complementary patterns composed of rounded nano-object miniarrays were investigated. In case of illumination with linearly and circularly polarized light the azimuthal orientation and handedness (in)dependence of (cross-polarized) copolarized transmitted signal components was proven for all types of patterns. Considerable (weak) asymmetric transmission was demonstrated in extended bands exclusively for both types of copolarized (cross-polarized) signals transmitted through single layer of convex miniarrays. Three-dimensional structures constructed with convex-concave-convex complex pattern-layers resulted in a negative index at the visible region boundary both for linearly and circularly polarized light illuminations. This is because dipolar modes on the convex nano-objects are synchronized with co-existent reversal dipoles on the concave nano-objects via interlayer coupling. Although during linearly polarized light illumination, the interlayer interaction decouples the localized and propagating modes excitable on the concave pattern in the 90° azimuthal orientation, the synchronization via tilted-rotating nanoring dipoles is almost perfect in the 0° azimuthal orientation. For circularly polarized light illumination, both the dispersion maps and the negative index phenomena synthesize the characteristics of the two orthogonal linearly polarized light illuminations. Important aspect is the appearance of a small/intermediate (large) time-averaged amplitude magnetic dipole due to the tilted (twisted) electric dipole on the concave nanoring, which less/more quickly turns (continuously rotates) with large/intermediate (small) out-of-plane tilting, when illumination is realized with linearly polarized light in the 90°/0° azimuthal orientation (with circularly polarized light). The location of the negative index can be predicted based on the copolarized transmittance signals computed for circularly polarized light illumination by using the linear base representation of Jones transmission matrix elements.
研究了由圆形纳米物体微阵列组成的单层和多层亚波长周期性 Babinet 互补图案。对于线偏振光和圆偏振光的照明，证明了所有类型的图案中，（交叉）偏振的同偏振传输信号分量的方位角取向和手性（内）依赖性。对于通过单层凸微阵列传输的两种类型的共偏振（交叉偏振）信号，在扩展的频带中展示了相当大的（弱）不对称传输。由凸-凹-凸复合图案层构成的三维结构导致在可见光区域边界处对于线偏振光和圆偏振光的照明均具有负折射率。这是因为在凸纳米物体上的偶极子模式通过层间耦合与在凹纳米物体上共存的反转偶极子同步。尽管在线偏振光照明时，层间相互作用使在 90°方位角上可激发的局域和传播模式在凹图案中解耦，但通过倾斜旋转纳米环偶极子的同步几乎在 0°方位角上是完美的。对于圆偏振光照明，色散图和负折射率现象综合了两种正交线偏振光照明的特性。重要的方面是由于凹纳米环上的倾斜（扭曲）电偶极子出现小/中等（大）时间平均幅度磁偶极子，这使得当以 90°/0°方位角的线偏振光（用圆偏振光）进行照明时，其小/中等（大）的出射倾斜时的翻转（连续旋转）更快/更慢。负折射率的位置可以根据用琼斯传输矩阵元素的线性基表示计算出的用于圆偏振光照明的共偏振透射信号来预测。
