Fig. 1. Electromagnetic interaction mechanisms of three kinds of typical optical antennas. (a) Optical antenna unit based on PB phase； (b) Optical antenna unit based on LSPR； (c) Optical antenna unit based on Mie resonance

Fig. 2. Typical terahertz (THz) metasurfaces for wavefront modulation. (a) THz metasurface lens and verification of its focusing and imaging performance; (b) THz meta-hologram and the alphabets reconstructed at different positions; (c) THz metasurfaces for generating the vortex beams with different topologies and the phase distribution of the generated vortex fields; (d) THz coded metasurfaces and the experiment results of beam deflection

Fig. 3. Multifunctional metasurfaces for wavefront modulation in the THz waveband. (a) Schematic diagram of a wavelength multiplexed metasurface and the images obtained at 0.5 THz and 0.63 THz, respectively; (b) Polarization multiplexed metasurface lens based on PB phase and the experimental results of the focusing results for incident wave with different polarizations; (c) Polarization multiplexed all-dielectric metasurface based on Mie resonance for vortex/Bessel beam generation and the measured intensity distributions under x- and y-polarized incidence, respectively

Fig. 4. Temperature-controlled metasurface device for THz wavefront modulation. (a) Tunable THz metasurface lens consisting of metasurface lens with V-shaped antennas and a VO₂ film; (b) Tunable metasurface lens and ring-Airy beam generator with C-shaped slots formed by etching the VO₂ film directly; (c) Tunable THz meta-hologram consisting of C-shaped gold antenna with VO₂

Fig. 5. (a) Schematic of the photo-induced THz plasmonic metasurface for wavefront modulation; (b) Design of photo-induced antennas based on PB phase; (c) Meta-hologram projected on the silicon wafer captured by charge-coupled device (CCD)

Fig. 5. [in Chinese]