title: A Reconfigurable Active Huygens' Metalens.
abstract: Metasurfaces enable a new paradigm to control electromagnetic waves by manipulating subwavelength artificial structures within just a fraction of wavelength. Despite the rapid growth, simultaneously achieving low-dimensionality, high transmission efficiency, real-time continuous reconfigurability, and a wide variety of reprogrammable functions is still very challenging, forcing researchers to realize just one or few of the aforementioned features in one design. This study reports a subwavelength reconfigurable Huygens' metasurface realized by loading it with controllable active elements. The proposed design provides a unified solution to the aforementioned challenges of real-time local reconfigurability of efficient Huygens' metasurfaces. As one exemplary demonstration, a reconfigurable metalens at the microwave frequencies is experimentally realized, which, to the best of the knowledge, demonstrates for the first time that multiple and complex focal spots can be controlled simultaneously at distinct spatial positions and reprogrammable in any desired fashion, with fast response time and high efficiency. The presented active Huygens' metalens may offer unprecedented potentials for real-time, fast, and sophisticated electromagnetic wave manipulation such as dynamic holography, focusing, beam shaping/steering, imaging, and active emission control.
authors.affiliation: School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Chen
authors.affiliation: School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China.
authors.forename: Yijun
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Department of Electrical and Computer Engineering, The University of Texas at Austin, 1 University Station C0803, Austin, TX, 78712, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Monticone
authors.affiliation: School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China.
authors.forename: Junming
authors.initials: J
authors.lastname: Zhao
authors.affiliation: School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhu
authors.affiliation: School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Jiang
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore.
authors.forename: Yongjune
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Microwave Engineering, Harbin Institute of Technology, Harbin, 150001, China.
authors.forename: Xumin
authors.initials: X
authors.lastname: Ding
authors.affiliation: School of Physics & Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Shuang
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Electrical and Computer Engineering, The University of Texas at Austin, 1 University Station C0803, Austin, TX, 78712, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Alù
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore.|NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou, 215123, China.|SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Shenzhen University, Shenzhen, 518060, China.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Qiu
keywords: Huygens' metalens; active metasurfaces; dynamic focusing; reconfigurable