Zhang Houjiao, Liu Zhengqi, Zhong Haozong, Liu Guiqiang, Liu Xiaoshan, Wang Junqiao
Opt Express. 2020 Nov 23;28(24):37049-37057. doi: 10.1364/OE.405625.
In this work, we numerically demonstrate a new facile strategy for all-dielectric broadband optical perfect absorbers. A monolayer refractory titanium oxide and nitride (TiN/TiO) core-shell nanowires array is used to form the grating on the opaque TiN substrate. Multiple resonant absorption bands are observed in the adjacent wavelength range, which therefore leads to the formation of an ultra-broadband absorption window from the visible to the infrared regime. The maximal absorption reaches 95.6% and the average absorption efficiency in the whole range (0.5-1.8 µm) is up to 85.4%. Moreover, the absorption bandwidth can be feasibly adjusted while the absorption efficiency can be still maintained in a high level via tuning the polarization state. Furthermore, the absorption window is observed to be highly adjustable in the wavelength range, showing a nearly linear relationship to the shell's index. These features not only confirm the achievement of the broadband perfect absorption but also introduce feasible ways to artificially manipulate the absorption properties, which will hold wide applications in metal-free plasmonic optoelectronic devices such as the solar harvesting, photo-detection, and thermal generation and its related bio-medical techniques.
在这项工作中，我们通过数值模拟展示了一种用于全介质宽带光学完美吸收体的新型简便策略。使用单层难熔氧化钛和氮化钛（TiN/TiO）核壳纳米线阵列在不透明的TiN衬底上形成光栅。在相邻波长范围内观察到多个共振吸收带，从而导致形成从可见光到红外波段的超宽带吸收窗口。最大吸收率达到95.6%，在整个范围（0.5 - 1.8 µm）内的平均吸收效率高达85.4%。此外，通过调整偏振态，可以灵活调节吸收带宽，同时吸收效率仍可保持在较高水平。此外，观察到吸收窗口在波长范围内具有高度可调性，与壳层折射率呈现近似线性关系。这些特性不仅证实了宽带完美吸收的实现，还引入了人为操纵吸收特性的可行方法，这将在无金属等离子体光电器件中具有广泛应用，如太阳能收集、光电探测、热发电及其相关生物医学技术。
