The discrimination of enantiomers is crucial in biochemistry. However, chiral sensing faces significant limitations due to inherently weak chiroptical signals. Nanophotonics is a promising solution to enhance sensitivity thanks to increased optical chirality maximized by strong electric and magnetic fields. Metallic and dielectric nanoparticles can separately provide electric and magnetic resonances. Here we propose their synergistic combination in hybrid metal–dielectric nanostructures to exploit their dual character for superchiral fields beyond the limits of single particles. For optimal optical chirality, in addition to maximization of the resonance strength, the resonances must spectrally coincide. Simultaneously, their electric and magnetic fields must be parallel and π/2 out of phase and spatially overlap. We demonstrate that the interplay between the strength of the resonances and these optimal conditions constrains the attainable optical chirality in resonant systems. Starting from a simple symmetric nanodimer, we derive closed-form expressions elucidating its fundamental limits of optical chirality. Building on the trade-offs of different classes of dimers, we then suggest an asymmetric dual dimer based on realistic materials. These dual nanoresonators provide strong and decoupled electric and magnetic resonances together with optimal conditions for chiral fields. Finally, we introduce more complex dual building blocks for a metasurface with a record 300-fold enhancement of local optical chirality in nanoscale gaps, enabling circular dichroism enhancement by a factor of 20. By combining analytical insight and practical designs, our results put forward hybrid resonators to increase chiral sensitivity, particularly for small molecular quantities.

中文翻译：

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用于超灵敏手性检测的双纳米谐振器

对映异构体的区分在生物化学中至关重要。然而，手性传感由于固有的弱手性信号而面临重大限制。由于强电场和磁场使光学手性增加，纳米光子学是提高灵敏度的有前途的解决方案。金属和介电纳米粒子可以分别提供电和磁共振。在这里，我们提出了它们在混合金属 - 电介质纳米结构中的协同组合，以利用它们在超手性场中超越单个粒子限制的双重特性。为了获得最佳的光学手性，除了最大化共振强度之外，共振必须在光谱上重合。同时，它们的电场和磁场必须平行且 π/2 异相并在空间上重叠。我们证明了共振强度与这些最佳条件之间的相互作用限制了共振系统中可达到的光学手性。从一个简单的对称纳米二聚体开始，我们导出了阐明其光学手性的基本限制的封闭式表达式。在权衡不同类别二聚体的基础上，我们提出了一种基于现实材料的不对称双二聚体。这些双纳米谐振器提供强且去耦的电和磁共振以及手性场的最佳条件。最后，我们为超表面引入了更复杂的双构建块，在纳米级间隙中局部光学手性增强了 300 倍，使圆二色性增强了 20 倍。通过结合分析洞察力和实际设计，