Girich Aleksey, Ivzhenko Liubov, Kharchenko Ganna, Polevoy Sergey, Tarapov Sergey, Krawczyk Maciej, Kłos Jarosław W
O. Ya. Usikov Institute for Radiophysics and Electronics NAS of Ukraine, Kharkiv, Ukraine.
ISQI, Faculty of Physics, Adam Mickiewicz University, Poznan, Poland.
Sci Rep. 2024 Jul 16;14(1):16477. doi: 10.1038/s41598-024-67610-9.
The microstrip of modulated width is a realization of a one-dimensional photonic crystal operating in the microwave regime. Like any photonic crystal, the periodic microstrip is characterised by the presence of frequency bands and band gaps that enable and prohibit wave propagation, respectively. The frequency bands for microstrip of the symmetric unit cell can be distinguished by 0 or Zak phase. The sum of these topological parameters for all bands below a given frequency gap determines the value of the surface impedance at the end of the microstrip. We demonstrate that edge modes are absent in a finite microstrip terminated at both ends in the centres of unit cells, but they can be induced by adding the defected cells. Edge modes present at both ends of the microstrip enable microwave tunneling with high transitivity in the frequency gap with or without a change in phase. This has been demonstrated experimentally and developed in detail using numerical simulations and model calculations. The investigated system, with a doublet of edge modes in the frequency gap, can be considered as a narrow passband filter of high selectivity and characterised by a significant group delay.
调制宽度的微带是一种在微波波段工作的一维光子晶体的实现方式。与任何光子晶体一样，周期性微带的特征在于存在分别允许和禁止波传播的频带和带隙。对称单元胞微带的频带可以通过0或Zak相位来区分。在给定频率间隙以下所有频带的这些拓扑参数之和决定了微带末端的表面阻抗值。我们证明，在两端终止于单元胞中心的有限微带中不存在边缘模式，但可以通过添加缺陷单元来诱导它们。微带两端出现的边缘模式能够在频带间隙中实现具有高透射率的微波隧穿，无论相位是否改变。这已通过实验得到证明，并使用数值模拟和模型计算进行了详细研究。所研究的系统在频带间隙中有一对边缘模式，可以被视为具有高选择性的窄带通滤波器，其特征是具有显著的群延迟。
