Journal Article Thermal Tuning of High-Tc Superconducting Bi2Sr 2CaCu2 O8+δ Terahertz Metamaterial

Kalhor, S.  ,  Ghanaatshoar, M.  ,  Kashiwagi, T.  ,  Kadowaki, K.  ,  Kelly, M. J.  ,  Delfanazari, K.

9 ( 5 )  , p.1400308 , 2017-10 , IEEE
Impact Statement:We report on the first demonstration of a low loss and tunable metamaterial based on high-temperature superconducting BSCCO. BSCCO with large superconducting energy gap is the building block of a compact, powerful, continuous and coherent THz source which has been found promising to close the THz gap. Our proposed metamaterial can be integrated with BSSCO THz emitters to improve their functionalities.
Abstract:We introduce a class of low-loss subwavelength resonators and report the first demonstration of a high-temperature ( Tc) superconducting Bi 2Sr2 CaCu2O 8+δ (BSCCO) terahertz (THz) metamaterial. The numerical simulations and analytical calculations are performed to study the electromagnetic response of the subwavelength BSCCO split-ring resonators (SRRs) to the incident photons with energies below the superconducting gap energy. A transition of resonance strength is observed as a dip in resonance frequency for temperatures below BSCCO Tc. To interpret the transmission spectra, resonance switching, and frequency tuning of SRRs, we calculate the temperature dependent complex permittivity and surface impedance of a 200 nm thick unpatterned slightly underdoped BSCCO thin film. We compare the resonance tunability of SRRs made of the extremely disorder superconductor (BSCCO) with metamaterials made of a weakly disorder superconductor YBa2Cu3O7 (YBCO) and show that the resonance quality and frequency tuning are comparable for these two metamaterials. Our results may be useful for THz emitters and detectors developments, for instance, by integration of SRRs with BSCCO THz emitters and microstrip antennas, the device functionalities such as polarization, emission pattern directivity, and output power could be controlled and improved.

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