Toshihiro Nakanishi, Yosuke Nakata, Yoshiro Urade, Kunio Okimura,
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| (a) Photomicrograph of the metasurface. (b) Whole structure of the device. (c) Current–voltage characteristics between electrodes. (d) Current–resistance characteristics between electrodes. |
https://aip.scitation.org/doi/abs/10.1063/5.0019265
We demonstrate the broadband operation of a switchable terahertz quarter-wave plate achieved with an active metasurface employing vanadium dioxide. For this purpose, we utilize anisotropically deformed checkerboard structures, which present broadband characteristics compatible with deep modulation. Moreover, the metasurface is integrated with a current injection circuit to achieve state switching; this injection circuit can also be employed to monitor the electric state of vanadium dioxide. We estimate the Stokes parameters derived from the experimental transmission spectra of the fabricated metasurface and confirm the helicity switching of circularly polarized waves near a designed frequency of 0.66 THz. The relative bandwidth is evaluated to be 0.52, which is 4.2 times broader than that in a previous study.
The metasurface was fabricated with the help of the Kyoto University Nano Technology Hub, as part of the “Nanotechnology Platform Project” sponsored by the MEXT in Japan. The present research was supported by JSPS KAKENHI Grant Nos. 17K05075, 17K17777, and 20K05360 and the Shimadzu Science Foundation.
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