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Published May 9, 2018 | Supplemental Material
Journal Article Open

Dual-Gated Active Metasurface at 1550 nm with Wide (>300°) Phase Tunability


Active metasurfaces composed of electrically reconfigurable nanoscale subwavelength antenna arrays can enable real-time control of scattered light amplitude and phase. Achievement of widely tunable phase and amplitude in chip-based active metasurfaces operating at or near 1550 nm wavelength has considerable potential for active beam steering, dynamic hologram rendition, and realization of flat optics with reconfigurable focal lengths. Previously, electrically tunable conducting oxide-based reflectarray metasurfaces have demonstrated dynamic phase control of reflected light with a maximum phase shift of 184° ( Nano Lett. 2016, 16, 5319). Here, we introduce a dual-gated reflectarray metasurface architecture that enables much wider (>300°) phase tunability. We explore light-matter interactions with dual-gated metasurface elements that incorporate two independent voltage-controlled MOS field effect channels connected in series to form a single metasurface element that enables wider phase tunability. Using indium tin oxide (ITO) as the active metasurface material and a composite hafnia/alumina gate dielectric, we demonstrate a prototype dual-gated metasurface with a continuous phase shift from 0 to 303° and a relative reflectance modulation of 89% under applied voltage bias of 6.5 V.

Additional Information

© 2018 American Chemical Society. Received: January 25, 2018; Revised: March 6, 2018; Published: March 23, 2018. This work was supported by Samsung Electronics (G.K.S., R.S., and H.A.A.) and the Air Force Office of Scientific Research under Grant FA9550-16-1-0019 (R.A.P.). The authors used facilities supported by the Kavli Nanoscience Institute (KNI) and Joint Center for Artificial Photosynthesis (JCAP) at Caltech. The authors would like to thank Carol Garland for help with the TEM imaging. The authors gratefully acknowledge useful discussions with Dr. Yao-Wei Huang, Dr. Pin Chieh Wu, and Dr. Duhyun Lee. The authors also gratefully acknowledge Erin Burkett and Christina Burch from the Hixon Writing Center at Caltech for providing feedback and guidance on writing the manuscript. The authors declare no competing financial interest.

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