Fig. 1. Schematic diagram and SEM images of the (a), (b) CSRR and (c), (d) H-shaped complementary planar metamaterials. From Sample I to Sample VI, different numbers of splits are introduced and arranged in designed symmetry/asymmetry. Δx represents the horizontal displacement of the split from the center. The symmetry/asymmetry of the H-shaped air slit is modulated by introducing a vertical displacement Δy of the horizontal air slit shift along the y direction. The scale bars in the figure are all 500 nm.

Fig. 2. Experimental and simulated reflection spectra of (a) Sample I, (b) Sample II, (c) Sample III, (d) Sample IV, (e) Sample V, and (f) Sample VI. The solid curve in each experimental spectrum serves as a guide for easier comparison.

Fig. 3. Conventional mode analysis for Samples I–VI. (a), (d), (g), (j) Electric field distributions; (b), (e), (h), (k) charge distributions; (c), (f), (i), (l) current distributions. The big arrows serve as a guide to show the current directions at the metal/air surface. The symmetrically distributed currents in the plasmonic atom samples (I–III) are highlighted by green color, and the currents in the right atom of the plasmonic molecule samples (IV–VI) are highlighted by blue color.

Fig. 4. Conventional mode analysis for three H-shaped complementary planar metamaterials. (a), (b) Experimental and simulated reflection spectra; (c) electric field distributions; (d) charge distributions; (e) current distributions. The symmetrically distributed currents are highlighted by green color.

Fig. 5. Mode analysis based on PEMs for (a)–(d) Sample I and (e)–(h) Sample II. D, dipole-like; Q, quadrupole-like; H, hexapole-like; O, octopole-like charge distributions; SCD/SCQ/SCH/SCO, symmetrically coupled dipole-like/quadrupole-like/hexapole-like/octopole-like charge distributions; ASSCD/ASSCQ/ASSCH, antisymmetrically coupled SCD/SCQ/SCH modes.

Fig. 6. Mode analysis based on PEMs for Sample II′.

Fig. 7. Mode analysis based on PEMs for (a) Sample V and (b) Sample VI. The square and circle in (a) correspond to the positions of modes 2 and 3, respectively.