Crystalline metamaterials for topological properties at subwavelength scales

TL;DR

This paper demonstrates that subwavelength crystalline metamaterials can exhibit topological photonic phases, enabling compact, robust light transport at scales smaller than the wavelength, by patterning resonant elements onto specific lattices.

Contribution

It introduces a novel approach to realize topological phases in deep subwavelength metamaterials through lattice patterning, expanding the potential for compact photonic devices.

Findings

Subwavelength topological phases observed at microwave frequencies.

Crystalline metamaterials support complex nonlocal properties.

Potential for applications in compact, robust photonic systems.

Abstract

The exciting discovery of topological condensed matter systems has lately triggered a search for their photonic analogs, motivated by the possibility of robust backscattering-immune light transport. However, topological photonic phases have so far only been observed in photonic crystals and waveguide arrays, which are inherently physically wavelength scaled, hindering their application in compact subwavelength systems. In this letter, we tackle this problem by patterning the deep subwavelength resonant elements of metamaterials onto specific lattices, and create crystalline metamaterials that can develop complex nonlocal properties due to multiple scattering, despite their very subwavelength spatial scale that usually implies to disregard their structure. These spatially dispersive systems can support subwavelength topological phases, as we demonstrate at microwaves by direct field mapping. Our approach gives a straightforward tabletop platform for the study of photonic topological phases, and allows to envision applications benefiting the compactness of metamaterials and the amazing potential of topological insulators.