Fig. 1. (a) Schematic of the polarization-dependent metamaterial-perovskite THz device. A periodic array of CRRs and SRRs tailors the PIT resonance at different frequencies determined by incident polarizations. A thin perovskite film is deposited on the quartz substrate acting as a photoactive layer illuminated by optical pump pulses (400 nm). (b) Schematic view of the functional unit cell. The thickness of the quartz substrate is H=2  mm, the height of the Au metamaterial is h=127  nm, and the period is Px=150  μm, Py=110  μm. Geometric parameters of the structure are L1=120  μm, L2=50  μm, L11=26  μm, L12=25  μm, L21=50  μm, L22=18  μm, respectively. Inset presentation shows the crystal structure of T−CH3NH3PbI3 phases. Optical microscopic images of fabricated Au structures (c) before and (d) after covering a 55 nm perovskite thin film, where the scale bar represents 100 μm, and the inset picture shows the thickness of the perovskite film.

Fig. 2. (a) Simulated and (b) measured amplitude transmissions of the designed polarization-related metamaterial under illuminations of x-polarized (blue) and y-polarized (red) THz electric fields without perovskite coating. Dashed lines represent Fano-resonant frequencies for two polarized THz electric fields.

Fig. 3. Results of the optical modulation of anisotropic THz wave. Measured transmission spectra of the designed perovskite-based device of the (a) x-polarized and (c) y-polarized incident THz electric field under different pump powers. Corresponding numerically simulated transmission spectra of the (b) x-polarized and (d) y-polarized incident THz electric field under different conductivities of the perovskite thin film. The dashed lines mark the frequencies corresponding to the Fano resonance peaks.

Fig. 4. Calculated z-component field distributions in the transverse plane of the Au metasurface varying the conductivity of the perovskite film under the x-polarized THz electric field from 0 S/m to 960 S/m. Incident fields are normalized as 1 V/m.

Fig. 5. Calculated z-component field distributions in the transverse plane of the Au metasurface varying the conductivity of the perovskite film under the y-polarized THz electric field from 0 S/m to 1440 S/m. Incident fields are normalized as 1 V/m.

Fig. 6. Time-evolution dynamics of the metasurface-perovskite device. (a) Transient transmission spectra of the y-polarized THz electric field at different pump-probe delay values for an average pump fluence of 30  μJ/cm2. (b) Measured transient THz excitation dynamics for perovskite (CH3NH3PbI3) thin film spin-coated on the Fano-resonant metasurface implemented by using OPTP measurements for various pump fluences. Solid curves represent the fittings of recombination processes utilizing rate equations, where the dotted lines are measured by experiment.

Fig. 7. Normalized linear absorption and PL spectra of the spin-coated perovskite (CH3NH3PbI3) film. The PL and absorption peaks are located at 760 and 740 nm, respectively.

Fig. 8. Intrinsic THz spectra of SRR and CRR resonators along (a) x and (b) y directions. The near-field coupling effect between CRR and SRR is the origin of PIT resonance.

Fig. 9. Theoretical calculation results of the Lorentzian mechanical oscillator model along the (a) x-polarized and (b) y-polarized incident THz electric field.

Fig. 10. Group delay data extracted from experiment results as a function of pump fluence: (a) x-direction and (b) y-direction.

Fig. 11. Simulated results with a phonon mode at 1.0 THz in the perovskite thin film as a function of optical conductivity of the perovskite thin film.