Tunable and high quality factor Fano and toroidal dipole resonances in terahertz superconducting metamaterials

Abstract

We experimentally studied a series of terahertz (THz) metamaterials with asymmetric resonator structures made from superconducting niobium nitride or gold films. Fano and toroidal dipole resonances are excited in superconducting metamaterials and their quality factors are higher in comparison with those of gold samples. Superconducting samples possess good tuning behaviors for both Fano and toroidal dipole resonance frequencies due to the change of kinetic inductance under different temperatures. The superconducting samples also exhibit good slow light effect due to the sharp dispersion in transmission spectra. These tunable and low loss metamaterials possess great significance to the development of THz nonlinear and slow light devices.

A study on the electromagnetic mechanism of a flexible terahertz toroidal dipole metasurfaces

“…The effect of TDs was first considered by Zel'Dovich in 1958 in his explanation of ubiquitous destruction in nuclear physics [21]. TDs have many unique electromagnetic properties, such as unidirectional refraction, resonance transparency and anisotropy et al [22][23][24][25][26][27][28]. As shown in table 1, the comparison among the previous typically researches on the toroidal dipole MMs are listed.…”

Active Terahertz Modulator and Slow Light Metamaterial Devices with Hybrid Graphene-superconductor Coupled Split-ring Resonator Arrays

“…Engineered metamaterials facilitate a wide range of devices with a specific function from filtering to modulating the THz waves [3][4][5][6]. A large variety of exotic phenomena can be observed with metamaterials [7][8][9]. The electromagnetically induced transparency (EIT) as a quantum phenomenon enables the slowing down of the light velocity [10].…”

Terahertz Resonators Based on YBa2Cu3O7 High-Tc Superconductor

“…For operational frequencies increasing toward the terahertz (THz), infrared, and visible range, ohmic losses are strongly enhanced, reducing the quality factor of resonances and therefore their tunability. To overcome these drawbacks, the use of superconducting materials has been proposed and innovative metamaterial structures have been realized [17][18][19][20][21][22][23][24]. Several works showed the low-loss properties of superconductors at finite frequency and their sensitivity to external stimuli, such as temperature, magnetic field, and light-pulses, which can be exploited to provide a robust tunability of the device response [19][20][21][22][23][24].…”

“…To overcome these drawbacks, the use of superconducting materials has been proposed and innovative metamaterial structures have been realized [17][18][19][20][21][22][23][24]. Several works showed the low-loss properties of superconductors at finite frequency and their sensitivity to external stimuli, such as temperature, magnetic field, and light-pulses, which can be exploited to provide a robust tunability of the device response [19][20][21][22][23][24]. These stimuli affect the superconducting state in a different way [25].…”