(Invited) New Analytical Method of Near-Field Spectroscopy – hBN Polaritons in Heteronanotubes

Abstract

Near-field spectroscopy is a promising approach for materials nanocharacterization, with a hope to reach beyond trivial materials’ imaging with a high spatial resolution. In a typical method, one uses the spectral modulation of the image spatial scales, determined from such a set of features of near-field scanning maps as a wave pattern or clear wave reflections (if not merely taking the spectral modulation of the image intensity). Applicability of these methods is rather limited and more sophisticated analytical technique would be desirable.Most severe restriction of abovementioned spectral techniques happens when the material under study possesses spatial non-uniformities much smaller than the excitation wavelength. Then, the patterns are highly influenced by the wave diffraction and not reliable to detect spectral information (in other words, the wave patterns are distorted by interference and excitation localization, which prohibits determining intrinsic wave parameters as a function of excitation).We have developed a new analytical technique which allows true sub-wavelength resolution, since the image domain required for the wave pattern analysis could be substantially smaller than a wavelength. The method has been used for studying hBN polaritons in heteronanotubes, the new material developed in Prof. Maruyama group at University of Tokyo. Acknowledgement: This work has been partially supported by NSF DMR-2011839 (MRSEC) and DMR-2039351 (2DCC MIP).