Figure 4
From: Two-dimensional photonic crystal with ring degeneracy and its topological protected edge states
Spin-locking of an edge state at a four-port topological junction. (a) Schematic of a four-port topological junction constructed by four domains with rods shift up (red) or down (blue). A waveguide port excites a pseudo-spin up edge wave; spin-locking ensures that the edge wave can only couples into two of three domain walls and the transmission through port 2 is completed suppressed. (b) Numerical simulated energy flux intensity along the domain walls. The results agree well with above conclusion that the edge wave only travels along the top and bottom domain walls. Color scale: energy flux intensity at the normalized frequency (ωa0/2πc = 0.74).
