Strong light–matter coupling is of much interest for both fundamental research and technological applications. The recently studied bound state in the continuum (BIC) phenomenon in photonics with controlled radiation loss rate significantly facilitates the realization of the strong coupling effect. In this work, we report the experimental observation of room temperature strong coupling between quasi-BIC resonances supported by a zigzag metasurface array of germanium elliptical disks and the vibrational resonance of polymethyl methacrylate (PMMA) molecules in the mid-infrared. Based on the approach of tuning the quasi-BIC resonance by changing the thickness of the coated PMMA layer, we can easily observe the strong coupling phenomenon, manifested by significant spectral splitting and typical anti-crossing behaviors in the transmission spectrum, with the spectral distance between the two hybrid photon-vibration resonances significantly larger than the bandwidth of both the quasi-BIC resonance and the PMMA absorption line. Our results demonstrate that the use of quasi-BIC resonance in all-dielectric nanostructures provides an effective and convenient approach for the realization of strong coupling effect.

中文翻译：

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连续体准束缚态与中红外分子振动之​​间的强耦合

强光-物质耦合对于基础研究和技术应用都非常重要。最近研究的光子学中具有受控辐射损失率的连续谱（BIC）现象的束缚态显着促进了强耦合效应的实现。在这项工作中，我们报告了由锗椭圆盘的锯齿形超表面阵列支持的准 BIC 共振与中红外聚甲基丙烯酸甲酯 (PMMA) 分子的振动共振之间的室温强耦合的实验观察。基于通过改变涂层 PMMA 层的厚度来调整准 BIC 共振的方法，我们可以很容易地观察到强耦合现象，表现为透射光谱中显着的光谱分裂和典型的反交叉行为，两个混合光子振动共振之间的光谱距离明显大于准 BIC 共振和 PMMA 吸收线的带宽。我们的结果表明，在全电介质纳米结构中使用准BIC共振为实现强耦合效应提供了一种有效且便捷的方法。