Experimental evidence of selective generation and one-way conversion of parities in valley sonic crystals

Abstract

Valley pseudo-spin and its associated interface wave transport in sonic crystals has attracted increasing attention from researchers for the potential manipulation of acoustic waves. The topological interface state, projected from a specific valley, is valley-locked, and, thus, renders robust reflection immunity against defects. In this work, we report on the experimental observation of the different parity generations of interface states at two distinct zigzag interfaces. By designing a “C”-shaped domain wall, we experimentally demonstrated the parity generation and selective excitation of interface valley-locked states. Benefiting from different parities of the interface states, one-way valley parity conversion was verified in sonic crystals without breaking the time reversal symmetry. Our findings contribute to the applications in noise control, acoustic communication, and logic processing for topological functional devices with unidirectional responses.