Valley-locked waveguide transport in acoustic heterostructures

摘要

Schematic of A | B  | C structures consisting of three SC domains, A, B, and C. Each SC is an array of triangular rods in a hexagonal lattice with base vectors and . The rotation angle α defines the orientation of the triangular rods with respect to , which is 30° for A, 0° for B, and −30° for C. Band diagrams for A, B, and C. Left panel: projected band structure for A | B  | C. The shadowed area in the bulk gap (delimited by the two red dashed lines) of domain A or C marks the region in which the TVWSs, indicated by the green line, exclusively exist. The 0th and 1st bands are the other gapped waveguide states. Right panel: absolute pressure | P | (colors) and energy flux (arrows) fields, and the pressure phase (colors) field of the topological waveguide states in domain B. Variation in the width of the shadowed region with , the number of layers in B describing the width of the B domain. The cyan (magenta) lines or dots mark the lower (upper) boundary of the 0th, 1st, and 2nd bands. Left panel: simulated pressure fields at a frequency of 5.55 kHz in the A | B  | C structures with  = 1, 11, and 21; line sources, marked in red and mimicked by a line of 2, 12, and 22 discretized point sources, respectively, each in the layer separations, are perpendicularly placed inside the waveguides to excite the modes. Right panel: calculated total transmitted energy versus frequency for the three structures.