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Published September 14, 2016 | Submitted + Supplemental Material
Journal Article Open

Gate-Tunable Conducting Oxide Metasurfaces


Metasurfaces composed of planar arrays of subwavelength artificial structures show promise for extraordinary light manipulation. They have yielded novel ultrathin optical components such as flat lenses, wave plates, holographic surfaces, and orbital angular momentum manipulation and detection over a broad range of the electromagnetic spectrum. However, the optical properties of metasurfaces developed to date do not allow for versatile tunability of reflected or transmitted wave amplitude and phase after their fabrication, thus limiting their use in a wide range of applications. Here, we experimentally demonstrate a gate-tunable metasurface that enables dynamic electrical control of the phase and amplitude of the plane wave reflected from the metasurface. Tunability arises from field-effect modulation of the complex refractive index of conducting oxide layers incorporated into metasurface antenna elements which are configured in reflectarray geometry. We measure a phase shift of 180° and ∼30% change in the reflectance by applying 2.5 V gate bias. Additionally, we demonstrate modulation at frequencies exceeding 10 MHz and electrical switching of ±1 order diffracted beams by electrical control over subgroups of metasurface elements, a basic requirement for electrically tunable beam-steering phased array metasurfaces. In principle, electrically gated phase and amplitude control allows for electrical addressability of individual metasurface elements and opens the path to applications in ultrathin optical components for imaging and sensing technologies, such as reconfigurable beam steering devices, dynamic holograms, tunable ultrathin lenses, nanoprojectors, and nanoscale spatial light modulators.

Additional Information

© 2016 American Chemical Society. Received: February 7, 2016. Revised: August 6, 2016. This work was supported by Samsung Electronics and by the Hybrid Nanophotonics Multidisciplinary University Research Initiative Grant (Air Force Office of Scientific Research, FA9550-12-1-0024). The conducting oxide material synthesis design and characterization was supported by the U.S. Department of Energy (DOE) Office of Science grant DEFG02-07ER46405 (K.T. and H.A.A.) and used facilities supported by the Kavli Nanoscience Institute (KNI) and Joint Center for Artificial Photosynthesis (JCAP) at Caltech. Y.W.H. and D.P.T. acknowledge the support from Ministry of Science and Technology, Taiwan (Grants 103-2911-I-002-594, 104-2745-M-002-003-ASP, and 105-2745-002-002-ASP) and Academia Sinica (Grant AS-103-TP-A06). K.T. acknowledges funding from the Swiss National Science Foundation (Grant 151853). The authors would like to thank Rui Liu for Al2O3 deposition and Katherine Fountaine for useful discussions. Author Contributions: (Y.W.H. and H.W.H.L.) contributed equally to this work. Y.W.H., H.W.H.L., R.S., and H.A.A. designed and conceived the experiments. Y.W.H. and H.W.H.L. fabricated the samples. Y.W.H., H.W.H.L., and R.A.P developed the measurement setup and performed the experiments. Y.W.H., H.W.H.L., and K.T. performed materials characterizations. Y.W.H. and R.S. performed numerical simulations. Y.W.H., H.W.H.L., R.S., R.A.P., K.T., S.H., and H.A.A. wrote the paper. All authors discussed the results and commented on the manuscript. The authors declare no competing financial interest.

Attached Files

Submitted - 1511.09380.pdf

Supplemental Material - nl6b00555_si_001.pdf


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August 20, 2023
October 20, 2023