Optical tuning and ultrafast dynamics of high-temperature superconducting terahertz metamaterials

Singh Ranjan; Xiong Jie; Azad Abul K.; Yang Hao; Trugman Stuart A.; Jia Q. X.; Taylor Antoinette J.; Chen Hou-Tong

doi:10.1515/nanoph-2012-0007

Nanophotonics (Jul 2012)

Optical tuning and ultrafast dynamics of high-temperature superconducting terahertz metamaterials

Singh Ranjan,
Xiong Jie,
Azad Abul K.,
Yang Hao,
Trugman Stuart A.,
Jia Q. X.,
Taylor Antoinette J.,
Chen Hou-Tong

Affiliations

Singh Ranjan: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Xiong Jie: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Azad Abul K.: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Yang Hao: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Trugman Stuart A.: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Jia Q. X.: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Taylor Antoinette J.: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Chen Hou-Tong: Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

DOI: https://doi.org/10.1515/nanoph-2012-0007
Journal volume & issue: Vol. 1, no. 1
pp. 117 – 123

Abstract

Read online

Through the integration of semiconductors or complex oxides into metal resonators, tunable metamaterials have been achieved by a change of environment using an external stimulus. Metals provide high conductivity to realize a strong resonant response in metamaterials; however, they contribute very little to the tunability. The complex conductivity in high-temperature superconducting films is highly sensitive to external perturbations, which provides new opportunities in achieving tunable metamaterials resulting directly from the resonant elements. Additionally, superconducting metamaterials are expected to enable strong nonlinear response and quantum effects, particularly when Josephson junctions are integrated into the metamaterial resonant elements. Here we demonstrate ultrafast dynamical tuning of resonance in the terahertz (THz) frequency range in YBa2Cu3O7-δ (YBCO) split-ring resonator (SRR) arrays excited by near infrared femtosecond laser pulses. The photoexcitation breaks the superconducting Cooper pairs to create quasiparticles. This dramatically modifies the imaginary part of the complex conductivity and consequently the metamaterial resonance on an ultrafast timescale, although the real conductivity does not change significantly. We observed resonance switching accompanied by substantial frequency tuning as a function of photoexcitation fluence, which also strongly depends on the nanoscale thickness of the superconducting films. All of our experimental results agree with calculations using an analytical model, which takes into account the contributions of the complex conductivity of the YBCO films to SRR resistance and kinetic inductance. The theoretical calculations reveal that the increasing SRR resistance upon increasing photoexcitation fluence is responsible for the reduction of resonance strength, and changes in both the resistance and kinetic inductance cause the resonance frequency shifts.

Published in Nanophotonics

ISSN: 2192-8606 (Print); 2192-8614 (Online)
Publisher: De Gruyter
Country of publisher: Germany
LCC subjects: Science: Physics
Website: https://www.degruyter.com/journal/key/nanoph/html#submit

About the journal

Abstract

Keywords