Fig. 1. (a) Topological phase diagram of the filling anomaly C6v-symmetric PCs. The frequencies of the p (d) states at the Γ point are plotted as the blue (orange) curves. (b) Corner fractional charges for the filling anomaly PCs with Wannier centers at maximal Wyckoff positions. (c) Electric field distributions of the simulated and measured TCS with various splicing boundaries.

Fig. 2. (a) Numerically calculated eigenvalues in the two-corner, three-corner, and six-corner coupled systems with several zigzag splicing boundaries. The bulk, edge, and corner states are represented by black, orange, and red dots, respectively. (b)–(d) Simulated electric field distributions of the coupled TCS with two-corner, three-corner, and six-corner coupling.

Fig. 3. (a), (b) Simulated transmission spectrum of two-corner coupled structure excited by an LCP source located at the center of the 1D boundary; the amplitude (phase) is extracted from the A or B corner. (c), (d) Simulated (bottom) and measured (upper) electric field distribution of two-corner coupled structure with LCP source. (e), (f) Simulated (bottom) and measured (upper) electric field distributions of three-corner and six-corner coupled systems with chiral sources.

Fig. 4. (a) Simulated transmission spectrum of specific splicing structure excited by an LCP (RCP) source at the other corner. (b) Experimentally measured transmission spectrum with pseudospin-polarized excitation sources. (c) Simulated and measured electric field distribution for an RCP excitation. (d) Corresponding field distribution for an LCP excitation.

Fig. 5. Band structure for (a) shrunken photonic crystals, (b) honeycomb photonic crystals, and (c) expanded photonic crystals.

Fig. 6. (a), (b) Schematic diagram and simulated projected band structure of 1D zigzag splicing boundary. (c), (d) Directional excitation of edge states with a chiral source. (e)–(h) Corresponding spinful edge states for 1D armchair splicing boundary.

Fig. 7. Simulated eigenmodes with pure zigzag splicing boundaries in (a) trapezoidal, (b) rhombic, (c) triangular, and (d) hexagonal structures.

Fig. 8. Simulated eigenmodes with pure armchair splicing boundaries in (a), (b) hexagonal and (c), (d) triangular structures.

Fig. 9. Simulated eigenmodes of splicing structures combining zigzag and armchair boundaries.

Fig. 10. Simulated eigenmodes of special splicing structures where these six types of TCS can be independently excited. The bulk, edge, and corner states are represented by black, orange, and red dots, respectively.

Fig. 11. (a)–(c) Simulated amplitude and phase extracted from splicing corner of different structures excited by a chiral source. (d)–(f) Corresponding electric field distributions.

Fig. 12. (a) Simulated transmission spectrum of the quadrangular structure excited by an LCP (RCP) source at the other corner. (b), (c) Simulated electric field distributions for an LCP (RCP) excitation.

Fig. 13. Photographs of experimental samples with various splicing boundaries.