Development of a cryogenic passive-scattering-type near-field optical microscopy system

Passive scattering-type, scanning near-field optical microscopy (s-SNOM) has been employed to study localized, long-wavelength infrared (LWIR) surface waves without external illumination. Here, we develop a cryogenic passive s-SNOM instrument in a vacuum chamber with 4 K liquid-helium cooling. Notab...

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Bibliographic Details
Published in:Review of scientific instruments 2023-02, Vol.94 (2), p.023701-023701
Main Authors: Lin, Kuan-Ting, Weng, Qianchun, Kim, Sunmi, Komiyama, Susumu, Kajihara, Yusuke
Format: Article
Language:English
Subjects:
Background noise
Conduction electrons
Conductors
Electromagnetic fields
Electromagnetism
Low temperature environments
Microscopes
Microscopy
Near fields
Optical microscopy
Scattering
Silicon dioxide
Surface waves
Thermal noise
Vacuum chambers
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Summary:Passive scattering-type, scanning near-field optical microscopy (s-SNOM) has been employed to study localized, long-wavelength infrared (LWIR) surface waves without external illumination. Here, we develop a cryogenic passive s-SNOM instrument in a vacuum chamber with 4 K liquid-helium cooling. Notably, the extremely low-temperature environment inside the chamber enables the realization of passive near-field detection with low background thermal noise. The technique mainly utilizes a highly sensitive LWIR confocal optical system and a tuning fork-based atomic force microscope, and the near-field detection was performed at a wavelength of 10.2 ± 0.9 µm. In this paper, we discuss the cryogenic s-SNOM implementation in detail and report the investigation of thermally excited surface electromagnetic fields on a self-heated NiCr wire deposited on SiO2 at a temperature of 5 K. The origin of the surface electromagnetic fields was established to be the thermally excited fluctuating charges of the conduction electrons. The cryogenic s-SNOM method presented herein shows significant promise for application in a variety of spheres, including hot-carrier dissipation in ballistic conductors.
ISSN:0034-6748
1089-7623
DOI:10.1063/5.0133575