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Proceedings Paper

The properties of electromagnetic responses and optical modulation in terahertz metamaterials
Author(s): Wei Chen; Yulei Shi; Wei Wang; Qingli Zhou; Cunlin Zhang
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Paper Abstract

Metamaterials with subwavelength structural features show unique electromagnetic responses that are unattainable with natural materials. Recently, the research on these artificial materials has been pushed forward to the terahertz (THz) region because of potential applications in biological fingerprinting, security imaging, and high frequency magnetic and electric resonant devices. Furthermore, active control of their properties could further facilitate and open up new applications in terms of modulation and switching. In our work, we will first present our studies of dipole arrays at terahertz frequencies. Then in experimental and theoretical studies of terahertz subwavelength L-shaped structure, we proposed an unusual-mode current resonance responsible for low-frequency characteristic dip in transmission spectra. Comparing spectral properties of our designed simplified structures with that of split-ring resonators, we attribute this unusual mode to the resonance coupling and splitting under the broken symmetry of the structure. Finally, we use optical pump–terahertz probe method to investigate the spectral and dynamic behaviour of optical modulation in the split-ring resonators. We have observed the blue-shift and band broadening in the spectral changes of transmission under optical excitation at different delay times. The calculated surface currents using finite difference time domain simulation are presented to characterize these resonances, and the blue-shift can be explained by the changed refractive index and conductivity in the photoexcited semiconductor substrate.

Paper Details

Date Published: 3 November 2016
PDF: 6 pages
Proc. SPIE 10030, Infrared, Millimeter-Wave, and Terahertz Technologies IV, 100301R (3 November 2016); doi: 10.1117/12.2245829
Show Author Affiliations
Wei Chen, Beijing Institute of Technology (China)
National Space Science Ctr. (China)
Yulei Shi, Capital Normal Univ. (China)
Wei Wang, Capital Normal Univ. (China)
Qingli Zhou, Capital Normal Univ. (China)
Cunlin Zhang, Capital Normal Univ. (China)

Published in SPIE Proceedings Vol. 10030:
Infrared, Millimeter-Wave, and Terahertz Technologies IV
Cunlin Zhang; Xi-Cheng Zhang; Masahiko Tani, Editor(s)

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