General Framework of Bound States in the Continuum in an Open Acoustic Resonator
General Framework of Bound States in the Continuum in an Open Acoustic Resonator
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DOI：
10.1103/physrevapplied.18.054021
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发表时间：
2022-11-08
影响因子：
4.6
通讯作者：
Miroshnichenko, Andrey E.
中科院分区：
文献类型：
--
作者：
Huang, Lujun;Jia, Bin;Miroshnichenko, Andrey E.
连续介质中的束缚态（BICs）提供了一种在光子学和声学中实现高q共振的可行方法。在本工作中，我们提出了在耦合声波导谐振器系统中构造Friedrich-Wintgen (FW) BICs和偶然BICs的一般方法。我们证明了在闭合谐振腔中任意两个简并谐振可以实现FW bic，而不管它们是否具有相同或相反的宇称。此外，它们的特征模轮廓可以通过调整附加波导的位置来任意设计。这提示了一种有效的方法，可以将BICs的性质从FW BICs连续切换到对称保护BICs或意外BICs。此外，这种bic在耦合波导-谐振器系统中以矩形、椭圆和菱形等形状维持。这些有趣的现象可以用两能级有效非厄米哈密顿量很好地解释，其中两个强耦合简并模在形成这样的FW bic中起主要作用。此外，我们发现这样的开放系统还支持几何空间而不是动量空间中的偶然bic，通过调整附加波导的位置，这归因于波导与封闭腔的特征模之间的淬火耦合。最后，我们制作了一系列三维耦合谐振腔波导，并通过测量其透射谱，实验验证了FW BICs和意外BICs的存在。我们的结果补充了现有的声学BIC库，并为声学器件的设计提供了良好的途径，如吸声器、滤波器和传感器。
Bound states in the continuum (BICs) provide a viable way of achieving high -Q resonances in both photonics and acoustics. In this work, we propose a general method of constructing Friedrich-Wintgen (FW) BICs and accidental BICs in a coupled acoustic waveguide-resonator system. We demonstrate that FW BICs can be achieved with arbitrary two degenerate resonances in a closed resonator, regardless of whether they have the same or opposite parity. Moreover, their eigenmode profiles can be arbitrarily engineered by adjusting the position of the attached waveguide. This suggests an effective way of contin-uously switching the nature of the BICs from FW BICs to symmetry-protected BICs or accidental BICs. Also, such BICs are sustained in the coupled waveguide-resonator system with shapes such as rectangles, ellipses, and rhomboids. These interesting phenomena are well explained by the two-level effective non -Hermitian Hamiltonian, where two strongly coupled degenerate modes play a major role in forming such FW BICs. Additionally, we find that such an open system also supports accidental BICs in geometry space instead of momentum space via tuning the position of the attached waveguide, which is attributed to the quenched coupling between the waveguide and eigenmodes of the closed cavity. Finally, we fabricate a series of three-dimensional coupled resonator waveguides and experimentally verify the existence of FW BICs and accidental BICs by measuring the transmission spectra. Our results complement the current BIC library in acoustics and provide nice routes for designing acoustic devices, such as acoustic absorbers, filters, and sensors.