Rainbow Capture Based on Underwater Gradient Phononic Crystals

Abstract

Waves of different frequencies are located and captured at different positions, giving rainbow capture a wide range of potential applications in filtering, buffering, energy collection, and other fields. In this paper, we design a rainbow capture structure based on gradient phonon crystals. The edge states change due to the different structural parameters. By designing a gradient structure, the sound waves of different frequencies are separated and trapped at different boundary positions to form the acoustic rainbow effect. Incident waves from different directions produce significantly distinct rainbow trapping effect. The distance sound propagates when excited from the left is increasingly further, while the distance when excited from the right is increasingly shorter. Besides, the symmetrical rainbow effect has also been demonstrated in symmetrical gradient phonon crystals. This work provides a theoretical reference for achieving diverse multiwavelength devices in acoustic systems.