光子学报, 2020, 49 (5): 0512001, 网络出版: 2020-06-04
超越SNOM探针通光孔径尺寸的金属纳米间隙超分辨测量
Superresolving Measurement of the Metallic Nanogap beyond the Aperture Size of the SNOM Probe
纳米光子学 偶极天线 扫描近场光学显微镜 分辨率 探针 间隙表面等离激元 远场辐射速率 Nanophotonics Dipole antenna Scanning near-field optical microscope Resolution Probe Gap surface plasmon polariton Radiative emission rate
摘要
采用电磁场有限元方法, 数值模拟了孔径型扫描近场光学显微镜(aperture Scanning Near-field Optical Microscopy, a-SNOM)在照明模式下的工作过程.针对金偶极天线结构, 改变天线 长度和纳米间隙尺寸, 计算了a-SNOM探针孔径的远场辐射速率随探针端面中心坐标变化的扫描曲线, 实现了超越a-SNOM探针通光孔径尺寸的天线金属纳米间隙的超分辨测量, 对于100 nm通光孔径的 探针, 可分辨最小尺寸为10nm(0.016倍波长)的金属间隙.通过对比金属和介质偶极天线的a-SNOM探针远场辐射速率测量的计算结果, 表明天线金属纳米间隙的超分辨测量的实现是由于金属间隙表面 等离激元的激发.
Abstract
The working process of aperture Scanning Near-Field Optical Microscopy (a-SNOM) under the illumination mode is simulated by using the finite element method of electromagnetic field. With changing the length and nanogap size of the optical resonant dipole antenna, the scanning curves of the radiative emission rate as a function of the central coordinate of the a-SNOM probe end surface are calculated. A superresolving measurement of the metallic nano-gap of the antenna beyond the aperture size of the a-SNOM probe is realized. For the a-SNOM probe with an aperture size of 100 nm, the smallest size of the antenna nanogap that can be resolved is 10 nm (0.016 times of the wavelength). By comparing the calculated results of the measured radiative emission rate of the a-SNOM probe for the metal and the dielectric dipole antennas, it is shown that the realization of the superresolving measurement of the metallic nanogap is due to the excitation of the gap surface plasmon polariton.
武娜娜, 钟莹, 刘海涛. 超越SNOM探针通光孔径尺寸的金属纳米间隙超分辨测量[J]. 光子学报, 2020, 49(5): 0512001. WU Na-na, ZHONG Ying, LIU Hai-tao1. Superresolving Measurement of the Metallic Nanogap beyond the Aperture Size of the SNOM Probe[J]. ACTA PHOTONICA SINICA, 2020, 49(5): 0512001.