Subwavelength edge detection through trapped resonances in waveguides

TL;DR

This paper introduces a novel subwavelength acoustic imaging method that isolates and visualizes edges and small details by converting evanescent waves into propagative waves using trapped resonances in waveguides, achieving high resolution.

Contribution

It presents a new technique to detect subwavelength features by converting evanescent waves into propagative waves with trapped resonances, enabling edge detection at resolutions much smaller than the wavelength.

Findings

Achieves resolution about ten times smaller than the wavelength.

Enables visualization of edges aligned in different directions.

Uses waveguide resonances to convert evanescent to propagative waves.

Abstract

Lenses that can collect the perfect image of an object must restore propagative and evanescent waves. However, for efficient information transfer, e.g., in compressed sensing, it is often desirable to detect only the fast spatial variations of the wave field (carried by evanescent waves), as the one created by edges or small details. Image processing edge detection algorithms perform such operation but they add time and complexity to the imaging process. Here, we present a new subwavelength approach that generates an image of only those components of the acoustic field that are equal to or smaller than the operating wavelength. The proposed technique converts evanescent waves into propagative waves exciting trapped resonances in a waveguide, and it uses periodicity to attenuate the propagative components. This approach achieves resolutions about an order of magnitude smaller than the operating wavelength and makes it possible to visualize independently edges aligned along different directions.