Focusing characteristics optimization of composite near-field fiber probe based on surface plasmon

Xiaokai Yang; Shuming Yang; Shaobo Li; Xiaomin Wang

doi:10.1117/12.2523996

6 January 2020 Focusing characteristics optimization of composite near-field fiber probe based on surface plasmon

Xiaokai Yang, Shuming Yang, Shaobo Li, Xiaomin Wang

Proceedings Volume 11383, Sixth Asia Pacific Conference on Optics Manufacture; 113830A (2020) https://doi.org/10.1117/12.2523996
Event: Sixth Asia Pacific Conference on Optics Manufacture, 2019, Hong Kong, Hong Kong

Abstract

With the development of integrated circuits, MEMS devices and biotechnology, people are demanding more and more for the detection of complex micro-structures. The diffraction limit of light restricts the resolution of traditional optical microscopes. Near-field optical microscopes can avoid Rayleigh criterion and break through the diffraction limit by detecting the details of objects with evanescent waves to achieve super resolution measurement. The minimum resolution of 60nm can be achieved by balancing the light throughout and aperture size of the aperture SNOM. While, the resolution of the scattering SNOM depends on the curvature radius of the tip of the probe. The resolution below 20nm can be obtained, but the signal can be extracted by a composite interference optical system and phase-locked technology. People have continued to pursue the development of near-field optical microscope with more convenient, more reliable and smaller resolution. In this paper, a surface plasmon probe with the combination of aperture and scattering is presented. The structure is shown in the attached drawings. On the basis of a commercial AFM probe, a composite probe based on the combination of surface plasmon enhancement and scattering probe focusing was formed by coating SiO 2 probe and etching a single ring. The structure of the probe was optimized, in order to achieve larger enhancement of the light field. Furthermore, the combination of aperture SNOM illumination can greatly suppress background noise and achieve higher signal-to-noise ratio. By these two technologies, interference optical system and phase-locked technology can be avoided, thus simplifying the design of SNOM instruments. The finite-difference time-domain method is utilized to simulate and calculate the field distribution of the focusing spot and optimize the microstructure of the excited surface plasmon, which provides a strong theoretical support for the probe fabrication.

Citation Download Citation

Xiaokai Yang, Shuming Yang, Shaobo Li, and Xiaomin Wang "Focusing characteristics optimization of composite near-field fiber probe based on surface plasmon", Proc. SPIE 11383, Sixth Asia Pacific Conference on Optics Manufacture, 113830A (6 January 2020); https://doi.org/10.1117/12.2523996

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