Li Sichao, Simpson Robert E, Shin Sunmi
Department of Mechanical Engineering, Collage of Design and Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore.
School of Engineering, University of Birmingham, Edgbaston, B15 2TT, UK.
Nanoscale. 2023 Oct 12;15(39):15965-15974. doi: 10.1039/d3nr02079g.
A classical thermal source, such as an incandescent filament, radiates according to Planck's law. The feasibility of super-Planckian radiation has been investigated with sub-wavelength-sized sources in the last decade. In such sources, a crystal-dependent coupling of photons and optical phonons is possible at thermal energies corresponding to that at room temperature. This interaction can be used to tailor the far-field thermal emission in a coherent manner; however, understanding heat transfer during this process is still nascent. Here, we used a novel measurement platform to quantify thermal signals in a GeSbTe/SiO nanoribbon structure. We were able to separate and quantify the radiated and conducted heat transfer mechanisms. The thermal emission from the GeSbTe/SiO nanoribbons was enhanced by 3.5× compared to that of a bare SiO nanoribbon. Our model revealed that this enhancement was directly due to polaritonic heat transfer, which was possible due to the large and lossless dielectric permittivity of GeSbTe at mid-IR frequencies. This study directly probes the far-field emission with a thermal gradient stimulated by Joule heating in temperature ranges from 100 to 400 K, which bridges the gap between mid-IR optics and thermal engineering.
一个经典的热光源，比如白炽灯丝，会根据普朗克定律进行辐射。在过去十年里，人们利用亚波长尺寸的光源研究了超普朗克辐射的可行性。在这类光源中，在对应于室温的热能下，光子与光学声子之间可能存在依赖于晶体的耦合。这种相互作用可用于以相干方式调整远场热发射；然而，对这个过程中热传递的理解仍处于起步阶段。在这里，我们使用了一个新颖的测量平台来量化GeSbTe/SiO纳米带结构中的热信号。我们能够分离并量化辐射和传导的热传递机制。与裸SiO纳米带相比，GeSbTe/SiO纳米带的热发射增强了3.5倍。我们的模型表明，这种增强直接归因于极化子热传递，这是由于GeSbTe在中红外频率下具有大的且无损耗的介电常数而成为可能。这项研究在100至400 K的温度范围内，直接探测了由焦耳热激发的热梯度产生的远场发射，填补了中红外光学与热工程之间的空白。
