Article

# Tuning the Resonance in High-Temperature Superconducting Terahertz Metamaterials

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MPA-CINT, MS K771, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
(Impact Factor: 7.51). 12/2010; 105(24):247402. DOI: 10.1103/PhysRevLett.105.247402
Source: arXiv

ABSTRACT

In this Letter, we present resonance properties in terahertz metamaterials consisting of a split-ring resonator array made from high-temperature superconducting films. By varying the temperature, we observe efficient metamaterial resonance switching and frequency tuning. The results are well reproduced by numerical simulations of metamaterial resonance using the experimentally measured complex conductivity of the superconducting film. We develop a theoretical model that explains the tuning features, which takes into account the resistive resonance damping and additional split-ring inductance contributed from both the real and imaginary parts of the temperature-dependent complex conductivity. The theoretical model further predicts more efficient resonance tuning in metamaterials consisting of a thinner superconducting split-ring resonator array, which are also verified in subsequent experiments.

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Available from: Quanxi Jia, Dec 20, 2013
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• "As visible from the Fig.2(d,e) the experimental results are well reproduced by the 3D modeling performed with CST microwave studio using a surface impedance model for the superconductor. The small discrepancy between the simulated amplitude transmission and the measured one has already been observed in similar experiments [24] and can be ascribed to different causes. We believe the main reason is that the values for the complex conductivity are considered as frequency-independent in the simulations: this is not true and they present quite large variations especially when approaching the gap frequency: our resonator is in fact operating slightly below the gap (ν res = 440GHz < f gap = 730 GHz) and this simplification can explain the semiquantitative agreement between simulations and experiments. "
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• "A more quantitative picture can be obtained by extracting the transmission minimum and resonance frequency of the fundamental LC resonance around 0.5 THz, shown in figure 3. Note that for the 90 K spectra shown in figure 2(f), the resonance is not sufficiently well defined to reliably extract the resonance frequency so the 90 K data in figures 3(b) and (d) are evaluated at 0.51 THz for all field intensity. At low temperatures the fundamental LC resonance redshifts with increasing pulse energy, while closer to T c the resonance blue-shifts, similar to the behaviour discussed in our previous work on temperature tuning of a similar sample [17]. For all temperatures the transmission at the resonance increases with increasing incident intensity, indicating that the resonance is becoming weaker. "
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• "The current distribution at the upper resonance shown in figure 3(c) is the reverse. The spectral response exhibits a temperature tunable property, as has been demonstrated in other superconducting metamaterials [30] [31]. As the temperature goes down, the transparent window is more and more prominent. "
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