We propose a design of tunable double-band perfect absorbers based on the resonance absorption in acoustic metasurfaces with nesting helical tracks and deep-subwavelength thicknesses (< λ /30 with λ being the operation wavelength). By rotating the cover cap with an open aperture on the nesting helical tracks, we can tailor the effective lengths of resonant tubular cavities in the absorber at will, while the absorption peak frequency is flexibly shifted in spectrum and the acoustic impedance is roughly matched with air. The simulated particle velocity fields at different configurations reveal that sound absorption mainly occurs at the open aperture. Our experiment measurements agree well with the theoretical analysis and simulation, demonstrating the wide-spectrum and tunable absorption performance of the designed flat acoustic device.

中文翻译：

---

通过具有嵌套螺旋轨道的声学超表面来调节双波段完美吸收体

我们基于在具有嵌套螺旋形轨道和深亚波长厚度（<λ/ 30，其中λ为工作波长）的声学超表面中的共振吸收，提出了一种可调谐双频完美吸收体的设计。通过旋转在嵌套螺旋形轨道上有开孔的盖子，我们可以随意调整吸收器中共振管状腔的有效长度，而吸收峰值频率在频谱上可以灵活移动并且声阻抗与空气大致匹配。在不同配置下的模拟粒子速度场表明，吸声主要发生在开孔处。我们的实验测量结果与理论分析和仿真结果非常吻合，证明了所设计的平板声学设备的广谱和可调吸收性能。