Figure 1. Photograph of the fabricated samples.

(a) Photograph of a 2D coupled metamaterial ring lattice composed of 3 × 4 unit cells. The U-shape waveguides are the input and output ports for selectively exciting and extracting edge states with specific pseudo-spins. It is noteworthy that a ring is purposely removed to form a defect, as marked by the red dashed box. (b) Photograph of a unit cell composed of one lattice ring surrounded by four coupling rings with the radius R=77.4 mm. The red arrow shows that the waves in the lattice ring are carrying pseudo-spin-up, viz. propagating in clockwise. (c) Zoom-in photograph of the metamaterial waveguide marked by the black circle in a. The period of the waveguide is P=4.3 mm. The thickness and width of the metal plate is t=1.7 mm and w=17.2 mm.