Abstract:We demonstrate a millimeter-wave range metamaterial fabricated from cuprate superconductor. Two complementary metamaterial structures have been studied, which exhibit Fano resonances emerging from the collective excitation of interacting magnetic and electric dipole modes.Our interest in superconducting metamaterials is driven by the desire to develop low loss media supporting high quality resonances. Such resonances may be achieved in metamaterials with broken structural symmetry supporting Fano resonances [1] where the quality factor can be controlled by design and is only limited by the Joule losses. Cuprate superconductors show lower surface conductivity than copper at frequencies below 200 GHz even at liquid nitrogen temperatures (see Fig. 1a) and is a prime choice for developing such metamaterials. Here we report the first experimental data on observation of Fano resonances in superconducting metamaterials and demonstrate that their quality factor may be controlled by temperature. All our measurements were performed using a free-space setup, which is based on mm-wave test system equipped with horn antennas (see Fig. 1b) and liquid hellium cryostat.Our metamaterials were fabricated by etching arrays of both positive and negative forms of asymmetrically-split rings in 330 um thick film of high-temperature superconductor YBCO deposited on a low-loss sapphire substrate, as show in Figs. 2a and 2b. Electromagnetic properties of the superconducting structures were studied at temperatures above and below the critical temperature T c = 87.4 K in 75 -110 GHz range of frequencies. Our measurements clearly showed the appearance of the Fano resonances upon superconducting phase transition. The results of the measurements are presented on Figs. 2c and 2d, where we plot changes in the transmission spectra of the cuprate metamaterials with decreasing temperature (down to 77 K) relative to their room temperature state. Fano resonances in metamaterials with broken structural symmetry appear as a result of excitation of the so-called trapped mode (electromagnetic mode that is weakly coupled to free-space [1]), and can be seen to fully develop in

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In the plasmonic regime, an electromagnetic wave bounded to the surface of a conductor can be confined to a region much smaller than its wavelength in free space. A major problem of plasmonic technology, however, is associated with large losses that these surface modes exhibit, intimately linked to Ohmic resistance of metals. In this work, we show that due to their dominant kinetic inductance, superconductors are intriguing yet natural plasmonic media capable of supporting low-loss plasmon waves with extreme confinement and the potential to serve as information carriers in compact terahertz data processing circuits.The field of plasmonics, which deals with the optical properties of metallic nanostructures, is one of the most fascinating and fast-moving areas of photonics [1]. Its explosive growth in recent years has been driven by parallel advances in nano-fabrication technologies as well as a wealth of potential applications in areas ranging from bio-chemical sensing to solar power generation. The special interest in surface plasmon polaritons-bound oscillations of the electrons and light propagating along a metal surface-is based largely on the possibility that they may act as information carriers in highly integrated nanophotonic devices transforming the chip-scale data transport paradigm by bridging the gap between present-day electronic

Negative dielectric constant and dominant kinetic resistance make superconductors an intriguing plasmonic media. Here we report on the first study of one of the most important and disputed manifestations of plasmonics, the effect of extraordinary transmission through an array of subwavelength holes, using a perforated film of high-temperature superconductor.The effect of extraordinary transmission can be regarded as one of the most important and disputable phenomenon in the area of plasmonics. It was observed as sharp peaks in transmission spectra of nondiffracting periodic arrays of sub-wavelength holes made in thin metal films [1]. The transmission efficiency at those maxima exceeded unity (when normalized to the area of the holes), which was orders of magnitude greater than predicted by standard aperture theory. Such unusual optical properties were attributed to resonant coupling of light with plasmons mediated by periodic patterning of the metal films.Superconductors can be regarded as media with negative real dielectric constant and mainly kinetic resistance, and therefore electromagnetics of such structures falls into the domain of plasmonics. Here we report the first experimental data on observation of extraordinary transmission in a perforated nondiffracting superconducting film and demonstrate that the magnitude of the extraordinary transmission resonances can be controlled with temperature and increases dramatically upon superconducting phase transition.Our experiments were performed using a free-space setup, which is based on mm-wave test system equipped with horn antennas and a closed-cycle liquid-helium cryostat, as shown in Fig. 1a and 1b. The superconduting film had the thickness of 300 nm and was made of high-temperature superconductor YBCO deposited on a low-loss sapphire substrate. It was perforated by etching an array of 1 mm holes with the period of 2.7 mm (see Fig. 1c), which rendered the structure non-diffracting at frequencies below 110 GHz. Transmission of the perforated cuprate film was measured for normal incidence