Exceptional points in parity-time-symmetric subwavelength metamaterials

亚波长谐振器系统中的异常点增强小粒子检测

Exceptional point enhanced small particle detection in systems of subwavelength resonators

本文研究高对比度谐振器系统中微小粒子对亚波长谐振的影响，提出基于电容矩阵多重散射展开的方法，发现异常点能显著提升噪声环境下的传感灵敏度，并通过数值实验验证了重构技术。

Time-dependent high-contrast subwavelength resonators

In the field of metamaterials, many intriguing phenomena arise from having a structure which is periodic in space. In time-dependent structures, conceptually similar properties can arise, which nevertheless have fundamentally different physical implications. In this work, we study time-dependent systems in the context of subwavelength metamaterials. The main result is a capacitance matrix characterization of the band structure, which generalizes previous recent work on static subwavelength metamaterials. This characterization provides both theoretical insight and efficient numerical methods to…

二维声学超材料中亚波长共振的傅里叶-伽辽金方法

Fourier--Galerkin Methods for Subwavelength Resonances in two-dimensional Acoustic Metamaterials

提出一种傅里叶-伽辽金框架，通过边界积分公式的傅里叶模态投影和有效矩阵的渐近展开，将亚波长共振问题转化为低维非线性特征值问题，实现高效计算。

Topological phenomena in honeycomb Floquet metamaterials

We dedicate this paper to the topological analysis of subwavelength solutions in Floquet metamaterials. This work should be considered as a basis for further investigation on whether topological properties of the bulk materials are linked to the occurrence of edge modes. The subwavelength solutions being described by a periodically parameterized time-periodic linear ordinary differential equation $\left\{\frac{d}{dt}X = A_α(t)X\right\}_{α\in \mathbb{T}^d}$, we put ourselves in the general setting of periodically parameterized time-periodic linear ordinary differential equations and introduce a…

Asymptotic Floquet theory for first order ODEs with finite Fourier series perturbation and its applications to Floquet metamaterials

Our aim in this paper is twofold. Firstly, we develop a new asymptotic theory for Floquet exponents. We consider a linear system of differential equations with a time-periodic coefficient matrix. Assuming that the coefficient matrix depends analytically on a small parameter, we derive a full asymptotic expansion of its Floquet exponents. Based on this, we prove that only the constant order Floquet exponents of multiplicity higher than one will be perturbed linearly. The required multiplicity can be achieved via folding of the system through certain choices of the periodicity of the coefficient…

Mimicking the active cochlea with a fluid-coupled array of subwavelength Hopf resonators

We present a design for an acoustic metamaterial that mimics the behaviour of the active cochlea. This material is composed of a size-graded array of cylindrical subwavelength resonators, has similar dimensions to the cochlea and is able to reproduce the frequency separation of audible frequencies. Non-linear amplification is introduced to the model in order to replicate the behaviour of the cochlear amplifier. This formulation takes the form of a fluid-coupled array of Hopf resonators. We seek solutions based on a modal decomposition, so as to retain the physically-derived coupling between re…