Author Affiliations
1Tianjin University, Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Optoelectronic Information Technology (Ministry of Education of China), Tianjin, China2Shanxi Datong University, Institute of Solid State Physics and College of Physics and Electronic Science, Shanxi Province Key Laboratory of Microstructure Electromagnetic Functional Materials, Datong, China3Wuhan University of Technology, School of Information Engineering, Wuhan, China4Tianjin Normal University, College of Physics and Materials Science, Tianjin, China5City University of New York, Advanced Science Research Center, Photonics Initiative, New York, United States6City University of New York, Graduate Center, Physics Program, New York, United States7University of Hong Kong, Faculty of Science, Department of Physics, Hong Kong, China8University of Hong Kong, Department of Electrical and Electronic Engineering, Hong Kong, China9Guilin University of Electronic Technology, Guangxi Key Laboratory of Optoelectronic Information Processing, School of Optoelectronic Engineering, Guilin, China10Oklahoma State University, School of Electrical and Computer Engineering, Stillwater, Oklahoma, United Statesshow less
Fig. 1. Schematics of the metasurface and its supercell. (a) The metasurface is formed by an array of supercells, arranged in a square lattice with a period of 43.5 mm. The PB phase response of each supercell is controlled by an addressable wireless signal and can be independently tuned over 28 phase levels. The metasurface can be reprogrammed to realize custom functionalities including metalensing, focused vortex beam generation, and holographic imaging by a proper design of the PB phase distribution. (b) The PB phase control in each supercell is achieved by transmitting the torque from a stepping motor to the PB meta-atoms through a set of gears.
Fig. 2. PB phase response. (a) The top portion of the PB meta-atom is a pair of Archimedean spirals with the same geometric parameters: inner radius (1.9 mm), outer radius (4.3 mm), height (0.035 mm), width (0.4 mm), and number of turns (two turns). The pink and sky-blue dials schematically depict the PB phase control resolution and variation gradients for and , respectively. (b), (c) Measured amplitudes of and , respectively. (d), (e) Measured PB phase response of and , respectively, versus different rotation angles.
Fig. 3. Realization of metalensing. (a), (d), (g) Required rotation profiles to realize different metalens operations for RCP waves. (b), (e), (h) Measured electric field intensities () at 7 GHz on the focal plane. (c), (f), (i) Horizontal cuts of the metalens focal spots, with FWHMs = 42, 44, and 44 mm, respectively.
Fig. 4. Focused vortex beam generation. (a), (e), (i), (m) Required rotation profiles to generate focused vortex beams with the topological charges of , respectively. (b), (f), (j), (n) Measured electric intensity ) distributions and (c), (g), (k), (o) measured phase () distributions of different vortex beams, respectively, obtained at the focal plane. (d), (h), (l), (p) OAM amplitude extracted from the measured complex amplitudes of different vortex beams, respectively.
Fig. 5. Holographic imaging. (a)–(d), (i)–(l) Required rotation profiles to generate holographic images of Chinese characters “天津大学” (Tianjin University) and “大同云冈” (Datong Yungang), respectively. (e)–(h), (m)–(p) Corresponding measured electric field intensities () of holographic images obtained at .