Dynamic radiative cooling attracts fast-increasing interest due to its adaptability to changing environment and promises for more energy-savings than the static counterpart. Here we demonstrate enhanced infrared emission by thermally switching the excitation of magnetic polariton with microstructured vanadium dioxide (VO₂) metasurfaces fabricated via scalable and etch-free processes. Temperature-dependent infrared spectroscopy clearly shows that the spectral emittance of fabricated tunable metasurfaces at wavelengths from 2 to 6 μm is significantly enhanced when heated beyond its phase transition temperature, where the magnetic polariton is excited with metallic VO₂. The tunable emittance spectra are also demonstrated to be insensitive to incidence and polarization angles such that the VO₂ metasurface can be treated as a diffuse infrared emitter. Numerical optical simulation and analytical inductance-capacitance model elucidate the suppression or excitation of magnetic polariton with insulating or metallic VO₂ upon phase transition. The effect of enhanced thermal emission with the tunable VO₂ metasurface is experimentally demonstrated with a thermal vacuum test. For the same heating power of 0.2 W, the steady-state temperature of the tunable VO₂ metasurface emitter after phase transition is found to be 20 °C lower than that of a reference V₂O₅ emitter whose static spectral emittance is almost the same as that of the VO₂ metasurface before phase transition. The radiative thermal conductance for the tunable metasurface emitter is found to be 3.96 W/m²K with metallic VO₂ at higher temperatures and 0.68 W/m²K with insulating VO₂ at lower temperatures, clearly demonstrating almost 6-fold enhancement in radiative heat dissipation.

中文翻译：

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通过热切换具有可伸缩微结构化VO ₂超表面的磁极化子的激发来增强红外发射。

动态辐射冷却因其对变化的环境的适应性而吸引了快速增长的兴趣，并有望比静态辐射冷却节省更多能源。在这里，我们通过热切换磁极化子的激发与通过可扩展且无蚀刻工艺制造的微结构化二氧化钒（VO ₂）超表面来演示增强的红外发射。与温度有关的红外光谱清楚地表明，当加热到超过其相变温度时，所制造的可调超颖表面在2至6μm波长处的光谱发射显着增强，其中金属VO ₂激发了磁极化子。还证明了可调发射光谱对入射角和偏振角不敏感，因此VO ₂超颖表面可被视为扩散红外发射器。数值光学仿真和解析电感电容模型阐明了相变时绝缘或金属VO ₂对磁极化子的抑制或激发。通过热真空测试实验证明了可调VO ₂超表面增强的热辐射效果。对于相同的0.2 W加热功率，发现相变后可调VO ₂超表面发射器的稳态温度比参考V ₂ O ₅低20°C。静态光谱发射率与相变之前VO ₂超表面的静态光谱发射率几乎相同的发射器。在较高温度下使用金属VO ₂时，可调超表面发射器的辐射热导为3.96 W / m ² K，在较低温度下使用绝缘VO _2时为0.68 W / m ² K ，显然表明辐射增强了近6倍散热。