Calibration method for complex permittivity measurements using s-SNOM combining multiple probe tapping harmonics

• DOI: 10.1364/oe.523785
• Publication Date: 2024-06-07T07:00:06Z
• Authors: Dario Siebenkotten; Bernd Kästner; Manuel Marschall; Arne Hoehl; Shuhei Amakawa
• Keywords: 02 engineering and technology; 0210 nano-technology

Scattering-type scanning near-field optical microscopy (s-SNOM) enables sub-diffraction spectroscopy, featuring high sensitivity to small spatial permittivity variations of the sample surface. However, due complexity probe-sample interaction, quantitative extraction complex leads a computationally demanding inverse problem, requiring further approximation system an invertible model. Black-box calibration methods, similar those applied microwave vector network analyzers, allow without detailed electromagnetic modeling interaction. These however, are typically designed for stationary setups. In contrast, distance between and probe tip s-SNOM is periodically modulated differentiate interaction from far-field background via lock-in detection harmonics periodic motion. This paper proposes improved black-box method that takes account effects tapping, including its multiple harmonics, background. The validated operating in mid-infrared spectral range by applying it spectroscopic measurements silicon microstructures different but well characterized doping.