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超材料慢声器件具有非常灵活的相位控制能力,能够实现超薄的声透镜、声学整流器和声学自加速发生器等多种声学功能器件。但是,大多数慢声器件存在严重的色散、界面阻抗不匹配等问题,限制慢声器件只能在较窄的带宽工作。文章介绍了一种全新的螺旋型慢声器件,回顾了均匀螺距的螺旋结构超材料和螺距连续变化的螺旋结构超材料,深入分析了实现宽带零色散慢声器件和宽带高耦合效率的慢声器件的基本原理和设计规则。这些慢声器件可通过调整结构的螺距来灵活实现相位调节。最后,文章从数值和实验两个方面证明了按照一定规律排列的螺旋结构型超材料单元可以将入射的平面声波转换成按预设抛物线轨迹传输的艾里声束。
Metamaterial slow-sounding devices have a very flexible phase-control capability enabling a wide range of acoustical functions such as ultra-thin acoustic lenses, acoustic rectifiers and acoustic self-accelerating generators. However, most slow-sounding devices have severe dispersion, interface impedance mismatches, and other issues that limit the ability of slow devices to operate at narrower bandwidths. In this paper, a new type of spiral slow-sounding device is introduced. The spiral structure metamaterial with uniform pitch and spiral structure metamaterial with continuous pitch variation are reviewed. The slow-sounding effect of realizing the broadband zero-dispersion slow-moving device and broadband high-coupling efficiency Device basic principles and design rules. These slow-sounding devices allow for flexible phase adjustment by adjusting the pitch of the structure. Finally, the paper proves that spiral structured metamaterial units arranged according to a certain rule can transform the incident plane acoustic wave into the Airy beam which is transmitted according to the preset parabolic trajectory from the numerical and experimental aspects.