Spatial Bloch Oscillations In Acoustic Waveguide Arrays

We designed a type of acoustic waveguide supported by spoof acoustic surface waves. The effective refractive index of acoustic waveguide can be effectively tuned by tailoring the waveguide width to control the propagation of spoof acoustic surface waves. Based on the advantage of the tunable refractive index, we construct a discrete waveguide array with transverse refractive index gradients to simulate the time evolution of the probability waves of electron in a tight-binding lattice under an external electric field. Based on numerical simulations and experiments, we discuss the relationship between the spatial Bloch oscillations period and the transverse refractive index gradient. Furthermore, we also investigate the influence of the interval between waveguides on the amplitude of the Bloch oscillations. Our acoustic waveguide array maybe provides a versatile testbed to explore analogous quantum mechanical effects, such as Zener tunneling, Anderson localization, and massless Dirac dynamics in acoustic system.