  The latest advances in topological physics have yielded a rich toolset to
design highly robust wave transfer systems, for overcoming issues like beam
steering and lateral diffraction in surface acoustic waves (SAWs). However,
presently used designs for topologically protected SAWs have been largely
limited to spin or valley-polarized phases, which rely on non-zero Berry
curvature effects. Here we propose and experimentally demonstrate a highly
robust SAW waveguide on lithium niobate (LiNbO3), based on a line defect within
a true triangular phononic lattice, which instead employs an intrinsic
chirality of phase vortices and maintains a zero Berry curvature. The guided
SAW mode spans a wide bandwidth and shows confinement in the lateral direction
with 3 dB attenuation within half of the unit-cell length. SAW routing around
sharp bends has been demonstrated in such waveguide, with less than ~4%
reflection per bend. The waveguide has also been found robust for defect lines
with different configurations. The fully on-chip system permits unidirectional
SAW modes that are tightly bound to the waveguide, which provides a compact
footprint ideal for miniaturization of practical applications and offers
insight into the possibility of manipulating highly focused SAW propagation.
