Xu Yi, Gao Baowei, He Axin, Zhang Tongzhou, Zhang Jiasen
State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
Institute of Navigation and Control Technology, China North Industries Group Corporation, Beijing 100089, China.
Nanophotonics. 2022 Feb 3;11(6):1167-1176. doi: 10.1515/nanoph-2021-0754. eCollection 2022 Feb.
Optical displacement metrology is important in nanotechnology and used to identify positions and displacements of nanodevices. Although several methods have been proposed, a sensor with ultracompact size, angstrom-scale resolution, and large measurement range is still lacking. We propose an optical displacement sensor with wavelength modulation that can demonstrate subwavelength footprint and angstrom-level resolution with large measurement range in this study. The proposed sensor consists of two optical slot antennas. Surface plasmon polaritons (SPPs) are launched at antennas and interfere when a tightly focused broadband light source illuminates the sensor. Spectrum of output SPPs presents a dip, which depends on the position of focal spot of incident light and is used to extract displacement. A maximum resolution of 0.734 nm was obtained. Furthermore, we used interference fringe of two broadband beams as light source and the measurement range of the sensor is not limited by the size of the tightly focused light source while maintaining high resolution. The method utilizes a new mechanism of wavelength modulation to overcome the trade-off between the high resolution and large measurement range, and achieve a variety of potential applications for nanometrology in the future.
光位移计量在纳米技术中很重要，用于识别纳米器件的位置和位移。尽管已经提出了几种方法，但仍缺乏一种尺寸超紧凑、具有埃级分辨率和大测量范围的传感器。在本研究中，我们提出了一种具有波长调制的光位移传感器，它可以展示亚波长尺寸、埃级分辨率以及大测量范围。所提出的传感器由两个光学狭缝天线组成。当一个紧聚焦的宽带光源照射传感器时，表面等离激元极化激元（SPP）在天线处产生并发生干涉。输出SPP的光谱呈现一个凹陷，它取决于入射光焦点的位置，并用于提取位移。获得了0.734纳米的最大分辨率。此外，我们使用两束宽带光束的干涉条纹作为光源，该传感器的测量范围不受紧聚焦光源尺寸的限制，同时保持高分辨率。该方法利用了一种新的波长调制机制，克服了高分辨率和大测量范围之间的权衡，并在未来实现了纳米计量学的各种潜在应用。
