Fig. 1. Schematic diagram of the unit cell with the corresponding structural parameters. (a) The perspective view, (b) the top view, and (c) the side view.

Fig. 2. Simulated (a) zeroth-order transmittance spectra, (b) reflection spectra, and (c) absorption spectra as a function of asymmetric degree d. (d)–(g) Simulated Re(H_z) patterns of the nanostructure corresponding to the absorption peak A, peak B, peak C, and peak D, respectively. (d) Simulated Re(H_z) patterns of the nanostructure with d = 60 nm at frequency f_A = 180.4 THz. (e), (f) Simulated Re(H_z) patterns of the nanostructure with d = 180 nm at frequency f_B = 189.1 THz and f_C = 167.2 THz, respectively. (g) Simulated Re(H_z) patterns of the nanostructure with d = 360 nm at frequency f_D = 173.7 THz.

Fig. 3. Simulated dispersion of the nanostructure with d = 0 nm (a)–(c), d = 180 nm (d)–(f), and d = 420 nm (g)–(i).

Fig. 4. Simulated (a) [or (d)] zeroth-order transmittance spectra, (b) [or (e)] reflection spectra, and (c) [or (f)] absorption spectra of the nanostructures with d = 60 nm (or d = 355 nm) as a function of P.

Fig. 5. Simulated (a) zeroth-order transmittance spectra and (b) reflection spectra of the nanostructures with d = 355 nm as a function of P. (c)–(f) Simulated Re(H_z) patterns of the nanostructure corresponding to the reflection peak E, peak F, peak G, and peak H, respectively. (c), (d) [or (e), (f)] Simulated Re(H_z) patterns of the nanostructure with P = 1160 nm (or P = 920 nm) at wavelength λ_E = 1.72 µm and λ_F = 1.79  µm (or λ_G = 1.63 µm and λ_H = 1.73 µm), respectively.

Fig. 6. CMT modelling of the bright-dark coupled resonators. FDTD-simulated (red circles) and CMT-fitted (blue solid curves) transmission spectra for samples with different d values of (a) 0 nm, (b) 40 nm, (c) 140 nm, (d) 260 nm, (e) 300 nm, and (f) 380 nm.

Fig. 7. Retrieved CMT parameters as functions of d.

Fig. 8. Retrieved (a), (c), (e) conventional and (b), (d), (f) generalized CMT parameters as functions of d.

Fig. 9. Based on Eqs. (41)–(43), retrieved α (a) and Imcκ (b) as functions of d.