title: Tunable microwave metasurfaces for high-performance operations: dispersion compensation and dynamical switch.
abstract: Controlling the phase distributions on metasurfaces leads to fascinating effects such as anomalous light refraction/reflection, flat-lens focusing, and optics-vortex generation. However, metasurfaces realized so far largely reply on passive resonant meta-atoms, whose intrinsic dispersions limit such passive meta-devices' performances at frequencies other than the target one. Here, based on tunable meta-atoms with varactor diodes involved, we establish a scheme to resolve these issues for microwave metasurfaces, in which the dispersive response of each meta-atom is precisely controlled by an external voltage imparted on the diode. We experimentally demonstrate two effects utilizing our scheme. First, we show that a tunable gradient metasurface exhibits single-mode high-efficiency operation within a wide frequency band, while its passive counterpart only works at a single frequency but exhibits deteriorated performances at other frequencies. Second, we demonstrate that the functionality of our metasurface can be dynamically switched from a specular reflector to a surface-wave convertor. Our approach paves the road to achieve dispersion-corrected and switchable manipulations of electromagnetic waves.
authors.affiliation: State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.|Air and Missile Defense College, Air force Engineering University, Xi'an, 710051, China.
authors.forename: He-Xiu
authors.initials: HX
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.|Department of Physics, Faculty of Science, Ningbo University, Ningbo 315211, China.
authors.forename: Shiwei
authors.initials: S
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.
authors.forename: Shaojie
authors.initials: S
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.
authors.forename: Weijie
authors.initials: W
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.|Air and Missile Defense College, Air force Engineering University, Xi'an, 710051, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Cai
authors.affiliation: Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Green Photonics and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Shulin
authors.initials: S
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.|Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: He
authors.affiliation: State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, China.|Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou