具有PT对称缺陷的周期亚结构中例外点的出现
Emergence of Exceptional Points in Periodic Metastructures with Hidden PT-symmetric Defects
摘要：
我们研究的弹性动力学的周期性的元结构，包括一个缺陷对，强制执行的奇偶校验时间（PT）对称性，由于一个明智的工程虚阻抗元件-一个具有能量放大（增益）和其他具有等效衰减（损失）机制。我们发现，它们的存在会影响初始能带结构的周期性厄米特亚结构，并导致形成许多例外点（EPs），主要位于带边缘的局部模式密度较高。PT对称缺陷的空间位置用作对相应光谱中出现的EP的数量以及创建第一EP所需的临界非厄米特（增益/损耗）强度的额外控制-特定缺陷位置使临界非厄米特强度最小化。我们使用有限元和耦合模理论为基础的模型来研究这些亚结构，并使用与时间无关的二阶微扰理论，以进一步证明的亚结构的大小和PT对称缺陷的位置上的最小非厄米特强度所需的创建在一个带中的第一个EP的影响。我们的研究结果激发了弹性动力学亚结构中EP实验实现的可行设计。
英文摘要：
We study the elastodynamics of a periodic metastructure incorporating a defect pair that enforces a parity-time (PT) symmetry due to a judiciously engineered imaginary impedance elements - one having energy amplification (gain) and the other having an equivalent attenuation (loss) mechanism. We show that their presence affects the initial band structure of the periodic Hermitian metastructure and leads to the formation of numerous exceptional points (EPs) which are mainly located at the band edges where the local density of modes is higher. The spatial location of the PT-symmetric defect serves as an additional control over the number of emerging EPs in the corresponding spectra as well as the critical non-Hermitian (gain/loss) strength required to create the first EP - a specific defect location minimizes the critical non-Hermitian strength. We use both finite element and coupled-mode-theory-based models to investigate these metastructures, and use a time-independent second-order perturbation theory to further demonstrate the influence of the size of the metastructure and the PT-symmetric defect location on the minimum non-Hermitian strength required to create the first EP in a band. Our findings motivate feasible designs for the experimental realization of EPs in elastodynamic metastructures.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
