热辐射的近场修饰

中文摘要 AI 辅助

亚波长距离下的辐射热传递通常被理解为相邻物体间光子隧穿介导的增强能量交换。近场相互作用虽能大幅增加相互热传递，但它是否改变物体自身发出的热辐射仍是个开放问题。本文通过实验表明，近场电磁耦合通过与距离相关的修饰发射率重塑远场热辐射。利用双探针量热平台，监测了两个硼硅酸盐微球在从远场到近场过渡距离范围内的辐射平衡。纳米瓦分辨的差分辐射测量揭示了不对称热流和较热球体的非单调响应，表明热辐射不仅受发射体 - 热库相互作用支配，还受与周围光子环境的耦合影响。通过分析耦合系统与外部热库之间交换的总功率，直接提取了修饰发射率，并表明近场相互作用通过重新分配热涨落可用的电磁模式使该对物体的远场热辐射重整化。这些观察结果提供了热发射体被其电磁环境修饰的直接实验证据，建立了珀塞尔效应的热模拟。

英文摘要

Radiative heat transfer at subwavelength distances is generally understood as enhanced energy exchange mediated by photon tunnelling between neighboring bodies. While near-field interactions can dramatically increase mutual heat transfer, whether they also modify the thermal radiation emitted by the bodies themselves remains an open question. Here we experimentally show that near-field electromagnetic coupling reshapes far-field thermal emission through a distance-dependent dressed emissivity. Using a dual-probe calorimetric platform, we independently monitor the radiative balance of two borosilicate microspheres over separations ranging from 120 micrometers to a few hundred nanometers, spanning the transition from the far field to the near field. Nanowatt-resolved differential radiometry reveals asymmetric heat fluxes and a non-monotonic response of the hotter sphere, demonstrating that thermal radiation is governed not only by emitter-bath interactions but also by coupling to the surrounding photonic environment. By analyzing the total power exchanged between the coupled system and the external thermal bath, we directly extract a dressed emissivity and show that near-field interactions renormalize the far-field thermal emission of the pair through a redistribution of the electromagnetic modes available to thermal fluctuations. These observations provide direct experimental evidence that thermal emitters are dressed by their electromagnetic environment, establishing a thermal analogue of the Purcell effect.

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