You Xiaolong, Upadhyay Aditi, Cheng Yongzhi, Bhaskaran Madhu, Sriram Sharath, Fumeaux Christophe, Withayachumnankul Withawat
Opt Lett. 2020 Mar 1;45(5):1196-1199. doi: 10.1364/OL.382458.
Far-infrared absorbers exhibiting wideband performance are in great demand in numerous applications, including imaging, detection, and wireless communications. Here, a nonresonant far-infrared absorber with ultra-wideband operation is proposed. This absorber is in the form of inverted pyramidal cavities etched into moderately doped silicon. By means of a wet-etching technique, the crystallinity of silicon restricts the formation of the cavities to a particular shape in an angle that favors impedance matching between lossy silicon and free space. Far-infrared waves incident on this absorber experience multiple reflections on the slanted lossy silicon side walls, being dissipated towards the cavity bottom. The simulation and measurement results confirm that an absorption beyond 90% can be sustained from 1.25 to 5.00 THz. Furthermore, the experiment results suggest that the absorber can operate up to at least 21.00 THz with a specular reflection less than 10% and negligible transmission.
具有宽带性能的远红外吸收器在包括成像、检测和无线通信在内的众多应用中有着巨大需求。在此，提出了一种具有超宽带操作的非谐振远红外吸收器。这种吸收器采用蚀刻到适度掺杂硅中的倒金字塔形腔的形式。通过湿法蚀刻技术，硅的结晶度将腔的形成限制为特定形状，其角度有利于有损硅与自由空间之间的阻抗匹配。入射到该吸收器上的远红外波在倾斜的有损硅侧壁上经历多次反射，并朝着腔底部耗散。模拟和测量结果证实，在1.25至5.00太赫兹范围内可保持超过90%的吸收率。此外，实验结果表明，该吸收器在镜面反射小于10%且透射可忽略不计的情况下，至少可工作到21.00太赫兹。
