Xu Jipeng, Jiang Xiaowei, Guo Chucai, Guo Yanting, Yan Rui, Zhang Jianfa, Zhu Zhihong, Tan Zhongqi, Liu Ken
College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, P. R. China.
Nanoscale. 2020 Sep 21;12(35):18049-18055. doi: 10.1039/d0nr02605k. Epub 2020 Jul 1.
Considerably subtle vibrations can be detected by light signals. Commonly, this is achieved based on the phase change of light that can be attributed to the vibration of a movable mirror, which has been used in gravitational wave detection. For a homogeneous dielectric membrane, the thinner the membrane, the greater the membrane vibration amplitude will be with respect to the sound pressure. However, if the membrane is too thin, most of the light will transmit through the membrane and the sensitivity will be reduced. To resolve this contradiction, we have developed a metasurface membrane with a thickness of only 50 nm but a considerably high reflectivity. This membrane is integrated with a 100-nm-thick gold membrane to form a cavity that can achieve perfect absorption of light. The vibration of the metasurface, which records the sound wave information, can change the light absorption. The noise equivalent pressure of the proposed structure is several orders lower than those of the recently reported optoacoustic detectors, and the alternating current signal response can be enhanced by approximately 1500 times compared with that of a membrane without a metasurface. The integration of nanomechanical oscillators and ultrathin membranes with a metasurface may facilitate future ultrasensitive sound and ultrasonic detection and benefit optomechanic design.
相当细微的振动可以通过光信号检测到。通常，这是基于光的相位变化来实现的，这种相位变化可归因于可移动镜子的振动，这已被用于引力波检测。对于均匀的介电膜，膜越薄，相对于声压，膜的振动幅度就越大。然而，如果膜太薄，大部分光将透过膜，灵敏度会降低。为了解决这一矛盾，我们开发了一种厚度仅为50纳米但反射率相当高的超表面膜。该膜与厚度为100纳米的金膜集成在一起，形成一个可以实现光完美吸收的腔体。记录声波信息的超表面的振动可以改变光吸收。所提出结构的噪声等效压力比最近报道的光声探测器低几个数量级，与没有超表面的膜相比，交流信号响应可以增强约1500倍。纳米机械振荡器和具有超表面的超薄膜的集成可能会促进未来的超灵敏声音和超声检测，并有利于光机械设计。
