Superconducting metamaterials

Abstract

Evanescent wave amplification has been predicted under the ideal condition that the index of refraction, n=−1+i0 precisely, but is difficult to observe in practice because current metamaterials suffer from high losses. We present experimental results on a metamaterial that employs superconducting Nb metals and low-loss dielectric materials. Results include transmission data on a wire, split-ring resonator, and a combination medium at temperatures between 4.2 and 297K. Evidence of negative effective permittivity, permeability, and a negative effective index passband are seen in the superconducting state between 50MHz and 18GHz. We find a dielectric loss of εeff,2=2.6×10−3 in a superconducting wire array at 10.75GHz.

Wide-band tuneability, nonlinear transmission, and dynamic multistability in SQUID metamaterials

“…In order to investigate the transfer of energy through the array, the SQUID that is located at the left end (i.e., that for n = 1) is excited by an ac flux field at a particular frequency. The system of equations (1) and equation (9) in the present case read…”

“…Superconductors, on the other hand, are intrinsically nonlinear materials, due to the extreme sensitivity of the superconducting state in external stimuli [7,8], which moreover exhibit significantly reduced Ohmic losses. They thus provide unique opportunities to the researchers in the field for the fabrication of superconducting metamaterials with highly controllable effective electromagnetic properties including wideband tuneability [9,10,11,12,13,14,15,16,17,18,19,20].…”

Electromagnetic Waves Propagation Characteristics in Superconducting Photonic Crystals

“…Dielectric losses are substantially reduced in the SC metals relative to analogous structures made of normal metals. The dielectric losses of such a SC nanomaterial are reduced by a factor of 6 upon penetrating into the SC state [15]. Indeed, studies of the optical properties of superconductor metal/dielectric multilayers are not numerous, may be the results have been used in the design of high reflection mirrors, beam splitters, and bandpass filters [16].…”

Low-frequency spectroscopy of superconducting photonic crystals

“…Photonic crystals (PCs) consisting of metallic wires are a subject of growing interest during last years and are widely studied both theoretically [1,2,3,4,5] and experimentally [6,7]. At low-frequencies, e.g., in the gigaand terahertz spectral regions, the real part of the dielectric function of metallic component is large and negative which allows the formation of the complete twodimensional photonic band gap in these spectral regions.…”