Li, Weimian, He, Jian, Dong, Daxing, Zhang, Guohao, Li, Xiao, Chen, Changdong, Liu, Youwen, and Fu, Yangyang
In this work, we propose an efficient approach for controlling acoustic waves through guided mode conversion within a single meta-layer comprised of gradient index metamaterials. By harnessing the subwavelength localization characteristics of acoustic surface waves, the meta-layer can be properly shaped to accommodate arbitrary and prospective trajectories, thus enabling flexible guidance and routing of acoustic waves. Utilizing such a mode conversion mechanism, the acoustic directional transmitter and beam splitter have been devised and numerically demonstrated based on Archimedean spiral structures. These acoustic devices can exhibit a broadband response, achieving transmission efficiency exceeding 80% over a specific bandwidth that can be controlled by the geometry design. The proposed gradient index meta-layer may open new possibilities for acoustic wave manipulation, enabling some promising applications in noise control, information transmission, and energy harvesting. • A single meta-layer is proposed to realize guided mode conversion. • The meta-layer can be shaped to guide sound waves along prospective trajectories. • Acoustic devices using meta-layers exhibit a high efficiency over a wide bandwidth. [ABSTRACT FROM AUTHOR]