Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling

TL;DR

This study demonstrates a low-loss perovskite superlens in the mid-infrared that achieves sub-wavelength imaging resolution and reveals enhanced probe-object coupling at specific distances, useful for various applications.

Contribution

The paper introduces a novel perovskite-based superlens for mid-infrared evanescent wave imaging with detailed near-field analysis and coupling enhancement insights.

Findings

Achieved imaging resolution of wavelength/14.

Observed maximum evanescent field coupling at specific probe distances.

Validated results with numerical simulations indicating enhanced probe-object interaction.

Abstract

A planar slab of negative index material works as a superlens with sub-diffraction-limited imaging resolution, since propagating waves are focused and, moreover, evanescent waves are reconstructed in the image plane. Here, we demonstrate a superlens for electric evanescent fields with low losses using perovskites in the mid-infrared regime. The combination of near-field microscopy with a tunable free-electron laser allows us to address precisely the polariton modes, which are critical for super-resolution imaging. We spectrally study the lateral and vertical distributions of evanescent waves around the image plane of such a lens, and achieve imaging resolution of wavelength/14 at the superlensing wavelength. Interestingly, at certain distances between the probe and sample surface, we observe a maximum of these evanescent fields. Comparisons with numerical simulations indicate that this maximum originates from an enhanced coupling between probe and object, which might be applicable for multifunctional circuits, infrared spectroscopy, and thermal sensors.