Kountouris George, Mørk Jesper, Denning Emil Vosmar, Kristensen Philip Trøst
Opt Express. 2022 Oct 24;30(22):40367-40378. doi: 10.1364/OE.472793.
We present a design for an optical dielectric bowtie cavity which features deep sub-wavelength confinement of light. The cavity is derived via simplification of a complex geometry identified through inverse design by topology optimization, and it successfully retains the extreme properties of the original structure, including an effective mode volume of V = 0.083 ± 0.001 (λ/2n) at its center. Based on this design, we present a modal analysis to show that the Purcell factor can be well described by a single quasinormal mode in a wide bandwidth of interest. Owing to the small mode volume, moreover, the cavity exhibits a remarkable sensitivity to local shape deformations, which we show to be well described by perturbation theory. The intuitive simplification approach to inverse design geometries coupled with the quasinormal mode analysis demonstrated in this work provides a powerful modeling framework for the emerging field of dielectric cavities with deep sub-wavelength confinement.
我们提出了一种光学介质蝴蝶结腔的设计，其特点是具有深亚波长光限制。该腔是通过对拓扑优化逆设计所确定的复杂几何结构进行简化而得到的，并且成功地保留了原始结构的极端特性，包括其中心处有效模式体积为V = 0.083±0.001(λ/2n)。基于此设计，我们进行了模态分析，结果表明在感兴趣的宽带范围内，珀塞尔因子可以由单个准正常模式很好地描述。此外，由于模式体积小，该腔对局部形状变形表现出显著的敏感性，我们证明微扰理论可以很好地描述这种敏感性。本文展示的逆设计几何结构的直观简化方法与准正常模式分析相结合，为具有深亚波长限制的介质腔新兴领域提供了一个强大的建模框架。
