Split-ring resonator (SRR) based metamaterials have been studied for the development of highly sensitive, small-sized, low-power chemical and biomolecular sensors. However, the anisotropic behavior arising from their two-dimensional (2D) structure presents substantial challenges leading to ambiguity in their transmission spectra. In this paper, we present the design of a three-dimensional (3D) isotropic octagram split-ring resonator (OSRR) demonstrating a three-dimensionally coupled resonance behavior that overcomes the anisotropic response of conventional 2D SRRs, leading to a strong, distortion-free, and polarization-invariant transmission response. The OSRR undergoes 3D coupling through the splits at the corners of the 3D structure (cube), which remains invariant under any polarization along the coordinate axes. The strong coupling between resonant segments provides the OSRR with 25 times higher sensitivity than the corresponding 2D structure, allowing the resonant frequency to be reliably monitored for small changes in concentration of a targeted substance. The isotropic frequency response of the 3D OSRR, without ambiguity in the amplitude caused by the polarization dependence, also allows monitoring the amplitude for minute changes in concentration that are too small to cause any shift in resonant frequency. Thus, the detection range for the presented 3D OSRR stretches from large to minute variations of targeted substance.

中文翻译：

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三维耦合太赫兹八卦作为各向同性超材料

已经对基于裂环谐振器（SRR）的超材料进行了研究，以开发高灵敏度，小型，低功耗的化学和生物分子传感器。然而，由其二维（2D）结构引起的各向异性行为提出了巨大的挑战，导致其透射光谱模糊不清。在本文中，我们介绍了一种三维（3D）各向同性八卦分叉环谐振器（OSRR）的设计，该谐振器展示了一种三维耦合谐振行为，该行为克服了常规2D SRR的各向异性响应，从而产生了强烈的，畸变的-自由且极化不变的传输响应。OSRR通过3D结构（立方体）角上的裂口进行3D耦合，在沿坐标轴的任何极化情况下，该裂隙都保持不变。共振段之间的强耦合为OSRR提供了比相应2D结构高25倍的灵敏度，从而可以针对目标物质浓度的微小变化可靠地监控共振频率。3D OSRR的各向同性频率响应不会因极化依赖性而引起的幅度模糊不清，也可以监视幅度，以观察浓度的微小变化，这些微小变化太小而不会引起谐振频率的任何偏移。因此，提出的3D OSRR的检测范围从目标物质的大变化到微小变化。3D OSRR的各向同性频率响应不会因极化依赖性而引起的幅度模糊不清，也可以监视幅度，以观察浓度的微小变化，这些微小变化太小而不会引起谐振频率的任何偏移。因此，提出的3D OSRR的检测范围从目标物质的大变化到微小变化。3D OSRR的各向同性频率响应不会因极化依赖性而引起的幅度模糊不清，也可以监视幅度，以观察浓度的微小变化，这些微小变化太小而不会引起谐振频率的任何偏移。因此，提出的3D OSRR的检测范围从目标物质的大变化到微小变化。