Superconducting plasmonics and extraordinary transmission

Abstract

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

Superconducting analogue of optical plasmonic waveguides

“…This is also reflected by the negligible imaginary part of the complex dielectric constant compare to the real part, which is negative. Therefore we argue that coupled excitations much like optical plasmons in metals should exist in the superconductors at frequencies that fall in the superconducting gap.Our previous experiments on extraordinary transmission through perforated superconducting films have indirectly shown the existence of the superconducting plasmons, which were held responsible for the enhancement of the effect upon superconducting transition [1]. Here we present the first direct evidence of highly localised plasmonic TM-modes supported by high-T c superconducting gap-and groove-waveguides of sub-micrometre lateral dimensions.…”

“…Our previous experiments on extraordinary transmission through perforated superconducting films have indirectly shown the existence of the superconducting plasmons, which were held responsible for the enhancement of the effect upon superconducting transition [1]. Here we present the first direct evidence of highly localised plasmonic TM-modes supported by high-T c superconducting gap-and groove-waveguides of sub-micrometre lateral dimensions.…”

Modulating Sub-THz Radiation with Current in Superconducting Metamaterial

“…The main focus of metamaterial research today is in developing new switchable and active media, predominantly through hybridizing metamaterial arrays with other functional materials [1]. Compared to the conventional metamaterials made using metallic resonators [2], the metamaterials fabricated from superconductors posses unique advantages that are linked to low Joule losses in the microwave and terahertz spectral ranges [3][4][5]. However, the most important advantages of the superconducting metamaterials are related to the nature of superconductivity.…”

“…For instance, the macroscopic quantum state of the supercon-ducting charge carriers makes superconducting metamaterials extremely sensitive to many external stimuli allowing quantum level nonlinearities with arrays containing Josephson Junctions [6][7][8][9][10][11][12], and with metamaterials exploiting the recently introduced quantum flux exclusion mechanism of nonlinearity [13]. Over the last decade researchers have demonstrated that light [14], magnetic field [15][16][17], and temperature [5,16,[18][19][20][21][22][23][24][25][26], can control the electromagnetic properties of the superconducting metamaterials. Here we demonstrate the control of electromagnetic properties of the metamaterial by running current through its metallic framework.…”

High-temperature superconducting multi-band radio-frequency metamaterial atoms

“…Nonetheless, RF metamaterials have been sought to improve the performance of magnetic resonance imaging (MRI) devices 6,7 , magnetoinductive lenses 8 , microwave antennas 9 , delay-lines 10 , and resonators 11 . Insofar as obtaining RF metamaterials substantially relies on the development of compact and scalable metamaterial atoms that are amenable to conventional microfabrication techniques, many superconducting structures have been recently introduced and tested for metamaterial applications in the RF/microwave regime [12][13][14][15][16][17][18][19][20][21] , motivated by their low-losses and deep sub-wavelength sizes.…”