Fig. 1. (a) Schematic of hybrid DSRR/RR metasurface. (b) Structure of unit cell. (c) Simulations of resonance transmission of the isolated DSRR, RR, and hybrid DSRR/RR. (d) Theoretical and simulated PIT spectra of hybrid DSRR/RR metasurface. (e) Calculation of the group delay at PIT resonance, with the curve of phase dispersion.

Fig. 2. PIT spectra in sample 1: (a) simulation, (b) experiment, (c) micrographs of the metasurface.

Fig. 3. PIT spectra in sample 2: (a) simulation, (b) experiment, (c) micrographs of the metasurface.

Fig. 4. Group delay in sample 1: (a) simulation results, (b) experimental results, and (c) variation of the group delay with polarization angle. Group delay in sample 2: (d) simulation results, (e) experimental results, and (f) variation with polarization angle.

Fig. 5. Surface current and electric field distributions of DSRR/RR at PIT frequency for (a) θ=0°, (b) θ=45°, and (c) θ=90°. Magnetic field distribution of DSRR/RR at PIT frequency for (d) θ=0°, (e) θ=45°, and (f) θ=90°.

Fig. 6. PIT spectra in sample 3: (a) simulation, (b) experiment, (c) micrographs of the metasurface.

Fig. 7. PIT spectra in sample 4: (a) simulation, (b) experiment, (c) micrographs of the metasurface.

Fig. 8. Group delay in sample 3: (a) simulation and (b) experiment. Group delay in sample 4: (c) simulation and (d) experiment. The inset shows the PIT transmittance contour plot with polarization angle and detuning frequency.

Fig. 9. Surface current and electric field distributions of FSRR/RR at PIT resonance under various polarization angle of (a) θ=0°, (b) θ=22.5°, and (c) θ=45°. Magnetic field distributions at (d) θ=0°, (e) θ=22.5°, and (f) θ=45°.

Fig. 10. Tunable PIT spectra of (a) theoretical reproduction, (b) numerical simulation, and (c) experiment under various pump power.

Fig. 11. Group delay of (a) the simulation and (b) the experiment in the FSRR/RR metasurface (sample 4), and (c) the variation of group delay with pump power.