Fig. 4

Topological transport of valley-polarized edge states. a Schematic diagram of the beam splitter used for selective excitation of valley-polarized edge states. The beam splitter comprises two domains of patterns A and two domains of patterns B. The black dashed lines and solid lines represent AB-type domain walls and BA-type domain walls, respectively. The red and blue arrows represent edges states near K and K′ valleys, respectively. b Photograph of the experiment setup. Two monopole antennas are used in experiments (see Methods section). DSPs are excited by one of the antennas and E _z component of the transmitted wave is measured by the other one. Inset shows a top-view photograph of the fabricated beam splitter. c, d Measured E _z amplitude ratio t _ij (outgoing terminal i, incident terminal j) when the source is placed at terminal 1 (c) or terminal 2 (d). The unshaded region corresponds to the bandgap obtained from experimental measurement