Fig. 3
From: Elastic pseudospin transport for integratable topological phononic circuits
Elastic topological whisper-gallery resonator. a Photograph of a topologically protected waveguide-coupled elastic resonator, consisting of one OI and two TIs. Two TI–OI interfaces exist as indicated by yellow dashed lines: one corresponding to a two-port straight waveguide on the left, the other corresponding to a hexagon-shaped waveguide on the right, i.e., a topological whisper-gallery resonator in an unconventional geometry. b Calculated dispersion of the elastic helical edge states, pseudospin+ is actually excited when we placed an ultrasonic transducer at the bottom of the straight waveguide. c Experimentally measured spectrum of elastic energy density inside the whisper-gallery resonator, having two distinct peaks at the frequencies of 108.55 kHz (at −k) and 110.09 kHz (at +k), respect to the Dirac frequency (at k = 0) of the helical edge states. The load Q-factor for the resonator modes at these two frequencies are remarkable exceeding 103. d, e Calculated and experimentally imaged elastic energy-density distributions for these two resonances, showing highly localized energy distribution inside the resonator
