Broadband non-reciprocity with robust signal integrity in a triangle-shaped nonlinear 1D metamaterial
Broadband non-reciprocity with robust signal integrity in a triangle-shaped nonlinear 1D metamaterial
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DOI：
10.1007/s11071-020-05520-x
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发表时间：
2020-02
影响因子：
5.6
通讯作者：
Lezheng Fang;Amir Darabi;A. Mojahed;A. Vakakis;M. Leamy
中科院分区：
文献类型：
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作者：
Lezheng Fang;Amir Darabi;A. Mojahed;A. Vakakis;M. Leamy
在本文中，我们提出并数值研究了一种非线性，非对称，无源超材料，实现巨大的非互易性与（i）宽带频率操作和（ii）强大的信号完整性。以往的研究表明，非线性和几何不对称性是必要的被动打破互惠。在这里，我们采用强非线性耦合，三角形不对称的细胞拓扑结构，和空间周期性，以最小的频率失真打破互易性。为了研究该系统的非线性能带结构，我们提出了一种新的表示法，即波数-频率-振幅能带结构，定量计算和分析了振幅相关色散。此外，我们观察和记录的新的非线性现象的时间延迟波的传输，从而在一个方向上的波传播最初受到阻碍，只有在持续时间延迟后恢复。基于数值证据，我们构建了一个非线性降阶模型（ROM），进一步研究这一现象，并表明它是由能量积累，不稳定性，以及ROM的某些非线性正常模式的不同分支之间的过渡。我们的研究结果的影响和可能的实际应用进行了讨论。
In this paper, we propose and numerically study a nonlinear, asymmetric, passive metamaterial that achieves giant non-reciprocity with (i) broadband frequency operation and (ii) robust signal integrity. Previous studies have shown that nonlinearity and geometric asymmetry are necessary to break reciprocity passively. Herein, we employ strongly nonlinear coupling, triangle-shaped asymmetric cell topology, and spatial periodicity to break reciprocity with minimal frequency distortion. To investigate the nonlinear band structure of this system, we propose a new representation, namely a wavenumber–frequency–amplitude band structure, where amplitude-dependent dispersion is quantitatively computed and analyzed. Additionally, we observe and document the new nonlinear phenomenon of time-delayed wave transmission, whereby wave propagation in one direction is initially impeded and resumes only after a duration delay. Based on numerical evidence, we construct a nonlinear reduced-order model (ROM) to further study this phenomenon and show that it is caused by energy accumulation, instability, and a transition between distinct branches of certain nonlinear normal modes of the ROM. The implications and possible practical applications of our findings are discussed.