Resonant modes within phononic crystals exhibit remarkable capabilities for the effective control of acoustic waves. In this study, we examine an underwater system comprising bilayer periodic polymethyl methacrylate rods and investigate the behaviors of Fabry-Perot bound states in the continuum (BICs) by adjusting the interlayer spacing parameter and the side length of rectangular rods. Additionally, we demonstrate the evolutionary trajectories of the Fabry-Perot BICs within a two-dimensional parameter space. During the evolution process, we observe fascinating phenomena such as merging, annihilation, and regeneration of BICs. Notably, the merging of BICs enables the achievement of high 𝑄 resonance across a broadened range of geometric parameters. The outcomes of this investigation present more opportunities for the design of robust acoustic devices.

中文翻译：

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在水下声子晶体内连续体中观察合并的法布里-珀罗束缚态


声子晶体中的共振模式表现出有效控制声波的卓越能力。在这项研究中，我们检查了一个包含双层周期性聚甲基丙烯酸甲酯棒的水下系统，并通过调整层间间距参数和矩形棒的边长来研究连续体 （BIC） 中法布里-珀罗结合态的行为。此外，我们还演示了二维参数空间内 Fabry-Perot BICs 的进化轨迹。在进化过程中，我们观察到 BIC 的合并、湮灭和再生等有趣的现象。值得注意的是，BIC 的合并能够在更广泛的几何参数范围内实现高 Q 谐振。这项研究的结果为设计鲁棒的声学器件提供了更多的机会。