Infrared super-resolution wide-field microscopy using sum-frequency generation

TL;DR

This paper demonstrates a novel super-resolution wide-field microscopy technique in the infrared range using sum-frequency generation, achieving a resolution of approximately one-ninth of the IR wavelength, enabling detailed imaging of nanostructures.

Contribution

The work introduces the first super-resolution IR microscopy method using sum-frequency generation in a wide-field setup, surpassing diffraction limits in this spectral range.

Findings

Achieved IR super-resolution of ~λ/9

Resolved polariton resonances in nanostructures

Differentiated spatial patterns of polariton modes

Abstract

Super-resolution microscopy in the visible is an established powerful tool in several disciplines. In the infrared (IR) spectral range, however, no comparable schemes have been demonstrated to date. In this work, we experimentally demonstrate super-resolution microscopy in the IR range ($\lambda_{IR}\approx 10-12\,\mu$m) using IR-visible sum-frequency generation. We operate our microscope in a wide-field scheme and image localized surface phonon polaritons in 4H-SiC nanostructures as a proof-of-concept. With this technique, we demonstrate an enhanced spatial resolution of $\sim\lambda_{IR}/9$, enabling to resolve the polariton resonances in individual sub-diffractional nanostructures with sub-wavelength spacing. Furthermore we show, that this resolution allows to differentiate between spatial patterns associated with different polariton modes within individual nanostructures.