论文标题
银/无定形 - 硅质双曲线材料的应变驱动的热和光学不稳定性
Strain-Driven Thermal and Optical Instability in Silver/Amorphous-Silicon Hyperbolic Metamaterials
论文作者
论文摘要
双曲线材料由于其几何设计的光学各向异性而显示出异常的光学特性，例如近乎完美的宽带吸收。他们的许多提议的应用，例如热伏洛尔电或辐射冷却，都需要高温稳定性。在这项工作中，我们将AG/A-SI多层作为模型系统，用于双曲线超材料的热稳定性。使用纳米摄影，有限元模拟和光谱法的组合，我们绘制了超材料的热和光学不稳定性。尽管热不稳定性在300℃下启动，但双曲线分散剂持续到500°C。在层状数据上的直接有限元模拟提供了将界面和弹性应变能量贡献对不稳定性贡献的途径。根据堆积顺序，由于热膨胀不匹配或最小化界面能量，不稳定的驱动力要么由各向异性弹性应变能的变化主导。我们的发现开辟了新的途径，以了解多层不稳定性，并为设计能够承受高温的双曲线超材料铺平了道路。
Hyperbolic metamaterials show exceptional optical properties, such as near-perfect broadband absorption, due to their geometrically-engineered optical anisotropy. Many of their proposed applications, such as thermophotovoltaics or radiative cooling, require high-temperature stability. In this work we examine Ag/a-Si multilayers as a model system for the thermal stability of hyperbolic metamaterials. Using a combination of nanotomography, finite element simulations and optical spectroscopy, we map the thermal and optical instability of the metamaterials. Although the thermal instability initiates at 300C, the hyperbolic dispersion persists up to 500C. Direct finite element simulations on tomographical data provide a route to decouple and evaluate interfacial and elastic strain energy contributions to the instability. Depending on stacking order the instability's driving force is either dominated by changes in anisotropic elastic strain energy due thermal expansion mismatch or by minimization of interfacial energy. Our findings open new avenues to understand multilayer instability and pave the way to design hyperbolic metamaterials able to withstand high temperatures.
