Chinese Physics B, Volume. 29, Issue 9, (2020)
Active metasurfaces for manipulatable terahertz technology
Fig. 1. (a) The electronic dispersion of graphene. (b) Calculated band structures of bulk MoS2 and monolayer MoS2. The arrows indicate the indirect and direct bandgaps, respectively. (a) Reproduced with permission from Ref. [
Fig. 2. (a) Schematics of the metasurface with the graphene transferred onto the array of Al mesas. (b) Phase modulation performance measured at different frequencies and gate biases. (c) The phase difference between waves at different polarizations. (d) Representation of coupled resonator structure. (e) The simulated transmission through the resonator as a function of frequency at different values of graphene conductivity. (a)–(c) Reproduced with permission from Ref. [
Fig. 3. (a) Illustration of a tunable metasurface consisting of graphene ribbons on a Ag mirror with a SiO2 gap layer. (b) Simulation result of reflectance spectra at different Fermi levels for the TM polarization. (c) 3D schematic representation of the complementary split-ring resonators-graphene hybrid metasurface on a SiO2/Si substrate. (d) The transmission modulation of the device operating at 4.5 THz. (a), (b) Reproduced with permission from Ref. [
Fig. 4. (a) Schematic of multilayer MoS2 dropped casted on asymmetric resonator under the illumination of the optical pump and THz probe pulses. The inset shows the cross-section of the unit cell. (b) Measured terahertz transmission spectra without MoS2 and with MoS2 at different optical pump fluences. (c) Schematic of WSe2 covered metasurface. (d) Power dependence of the THz transmission at different pump fluences. (e) Transient evolution of the ultrafast THz switching metasurface. (a), (b) Reproduced with permission from Ref. [
Fig. 5. (a) HRTEM image of monoclinic/rutile domain walls in VO2 and
Fig. 6. (a) Schematic energy diagram for THz-driven IMT in VO2 and resistivity hysteresis curves. (b) Illustration of the THz-pump/x-ray probe experiment and the relevant observable processes. (a) Reproduced with permission from Ref. [
Fig. 7. (a) Illustrations of metasurface with metal resonator patterns on a VO2 film and the transmission spectra at different temperatures. (b) Diagram of the VO2 based hybrid metasurface and the transmission spectra at different values of electric current. (c) The sketch of the metasurface and phase spectra with the increasing light power. (a) Reproduced with permission from Ref. [
Fig. 8. (a) Electric field distribution in Lorentzian and Fano resonators for YBCO and aluminum, respectively, the optical image of the fabricated Fano resonator samples. (b) Measured amplitude transmission spectra. (a), (b) Reproduced with permission from Ref. [
Fig. 9. (a) Measured transmission amplitude spectrum of the metasurface at different temperatures. (b) Planar geometry of NbN based metasurface. (c) THz transmission spectra at different temperatures. (d) Ultra-fast all-optical switch based on YBCO hybrid metasurface. (a) Reproduced with permission from Ref. [
Fig. 10. (a) Schematic of a superconducting NbN metasurface. (b) Effective surface reactance and resistance as a function of THz electrical field and (c) as a function of temperature. (d) The THz metasurface in which the light area is YBCO and the dark area is LaAlO3 substrate. (e) THz field strength-dependent transmission spectra at different temperatures. (a)–(c) Reproduced with permission from Ref. [
Fig. 11. (a) Schematic structure of isolator based on the MO metasurface. (b) The transmission spectrum of the forward waves and backward waves at
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Jing-Yuan Wu, Xiao-Feng Xu, Lian-Fu Wei. Active metasurfaces for manipulatable terahertz technology[J]. Chinese Physics B, 2020, 29(9):
Received: May. 18, 2020
Accepted: --
Published Online: Apr. 29, 2021
The Author Email: Wei Lian-Fu (lfwei@dhu.edu.cn)