Slow waves in locally resonant metamaterials line defect waveguides

Nadège Kaina (1) , Alexandre Causier (2) , Yoan Bourlier (2) , Mathias Fink (1) , Thomas Berthelot (2) , Geoffroy Lerosey (1)

1 IL - Institut Langevin - Ondes et Images (UMR7587)
2 LICSEN UMR 3685 - Laboratoire Innovation en Chimie des Surfaces et NanoSciences

The ability of electromagnetic waves to interact with matter governs many fascinating effects involved in fundamental and applied, quantum and classical physics. It is necessary to enhance these otherwise naturally weak effects by increasing the probability of wave/matter interactions, either through field confinement or slowing down of waves. This is commonly achieved with structured materials such as photonic crystal waveguides or coupled resonator optical waveguides. Yet their minimum structural scale is limited to the order of the wavelength which not only forbids ultra-small confinement but also severely limits their performance for slowing down waves. Here we show that line defect waveguides in locally resonant metamaterials can outperform these proposals due to their deep subwavelength scale. We experimentally demonstrate our approach in the microwave domain using 3D printed resonant wire metamaterials, achieving group indices n g as high as 227 over relatively wide frequency bands. Those results correspond to delay-bandwidth products, one of the slow wave devices figure of merit, 10 times higher than any proposal based on structured materials. We further prove that the delay-bandwidth product of metamaterial line defect waveguide is inversely proportional to the typical spatial scale of these composite media, a property that is unique to their resonant nature. Our findings, though demonstrated in the microwave domain for a specific structure, are very general and can be transposed to various resonant unit cells, frequency range and even other types of waves such as acoustic or elastic ones.

Domaines: Matériaux

Nadège Kaina, Alexandre Causier, Yoan Bourlier, Mathias Fink, Thomas Berthelot, et al.. Slow waves in locally resonant metamaterials line defect waveguides. 2016. ⟨cea-01310699⟩