Circular dichroism (CD) can distinguish the handedness of the chiral molecules. However, it is typically very weak due to vanishing absorption at low molecular concentrations. Here, we suggest thermal CD (TCD) for chiral detection, leveraging the temperature difference in the chiral sample when subjected to right- and left-circularly polarized excitations. The TCD combines the enantiospecificity of CD with the higher sensitivity of thermal measurements while introducing new opportunities in the thermal domain that can be synergistically combined with optical approaches. We propose a theoretical framework to understand the TCD of individual and arrays of resonators covered by chiral molecules. To enhance the weak TCD of chiral samples, we first used individual dielectric Mie resonators and identified chirality transfer and self-heating as the underlying mechanisms giving rise to the differential temperature. However, inherent limitations imposed by the materials and geometries of such resonators make it challenging to surpass a certain level in enhancements. To overcome this, we suggest nonlocal thermal and electromagnetic interactions in the arrays. We predict that a combination of chirality transfer to Mie resonators, collective thermal effects, and optical lattice resonance could, in principle, offer more than four orders of magnitude enhancement in TCD. Our thermonanophotonic-based approach thus establishes key concepts for ultrasensitive chiral detection.

中文翻译：

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用于手性传感的纳米光子增强热圆二色性


圆二色性 （CD） 可以区分手性分子的旋向性。然而，由于在低分子浓度下吸收消失，它通常非常弱。在这里，我们建议使用热 CD （TCD） 进行手性检测，利用手性样品在受到右圆和左圆极化激发时的温差。TCD 将 CD 的对映体特异性与热测量的更高灵敏度相结合，同时在热领域引入了可以与光学方法协同结合的新机会。我们提出了一个理论框架来理解手性分子覆盖的单个和阵列谐振器的 TCD。为了增强手性样品的弱 TCD，我们首先使用单独的电介质 Mie 谐振器，并确定手性转移和自热是产生温差的潜在机制。然而，这种谐振器的材料和几何形状所施加的固有限制使得在增强功能上超过一定水平具有挑战性。为了克服这个问题，我们建议在阵列中使用非局部热和电磁相互作用。我们预测，原则上，将手性转移到 Mie 谐振器、集体热效应和光晶格共振的组合可以在 TCD 中提供超过四个数量级的增强。因此，我们基于热纳米光子的方法建立了超灵敏手性检测的关键概念。