Bound states in the continuum (BICs) emerge throughout physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention in optics and photonics, and especially in metasurfaces, that is, planar arrays of sub‐wavelength meta‐atoms. One of their most outstanding features is the arbitrarily large Q‐factors they induce upon approaching the BIC condition, which is exploited here to achieve a narrow transparency band. It is first shown how to shift a canonical BIC in an all‐dielectric metasurface, consisting of high‐refractive disks exhibiting in‐ and out‐of‐plane magnetic dipole (MD) resonances, by tuning the periodicity of the array. By means of the coupled electric/magnetic dipole formulation, it is shown analytically that when the quasi‐BIC overlaps with the broad (in‐plane MD) resonance, a full transparency band emerges with diverging Q‐factor upon approaching the BIC condition in parameter space. Finally, the experimental measurements in the microwave regime with a large array of high‐refractive‐index disks confirm the theoretical predictions. The results reveal a simple mechanism to engineer an ultra‐narrow BIC‐induced transparency band that can be exploited throughout the electromagnetic spectrum with obvious applications in filtering and sensing.

中文翻译：

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连续谱中拟束缚态在全介电超表面中产生的高Q透明带

连续体中的束缚态（BIC）在整个物理学中都以渗漏/共振模式出现，但仍然高度局限。它们已经在光学和光子学领域引起了极大的关注，尤其是在超表面，即亚波长亚原子的平面阵列。它们最突出的特征之一是它们在接近BIC条件时会感应出任意大的Q因子，在这里可以利用它来实现狭窄的透明带。首先展示了如何通过调整阵列的周期性，在全介电超表面上移动规范BIC，该全介电超表面由表现出平面内和平面外磁偶极（MD）共振的高折射盘组成。通过耦合的电/磁偶极子公式，分析表明，当准BIC与宽（面内MD）谐振重叠时，在参数空间中接近BIC条件时，会出现一个完整的透明带，并且Q因子会发散。最后，在微波条件下使用大量高折射率圆盘进行的实验测量证实了理论预测。结果揭示了一种设计超窄BIC感应透明带的简单机制，该带可在整个电磁频谱中得到开发，并在滤波和传感中有明显的应用。