迷宫型声学超表面可调参数及其全相位调节

Tunable Parameters of Labyrinth Acoustic Metasurface and All-Phase Regulation

针对以往声学超表面研究的不足,提出一种亚波长迷宫型声学超表面结构;以迷宫型声学超表面物理特性的有效调控为目的,深入研究了各参数与声学超表面的关系,重点分析了声学超表面对反射相位的调节作用,实现了对声学超表面反射相位的人工调控。为了揭示声学超表面与各参数之间的内在联系,逐一分析了每个可调参数对声学超表面的吸声系数和反射相位的影响,结果表明:声学超表面盖板上小孔的直径、迷宫超表面原胞边长和迷宫槽宽对吸声系数和反射相位有决定性的影响,相对而言,迷宫棱宽和迷宫盖板的厚度对吸声系数和反射相位影响较小;盖板上的小孔直径越小,相应的共振频率就越低,吸声系数曲线向低频移动,而峰值保持不变,反射相位曲线也向低频移动,但相位轮廓保持不变;原胞边长越小,相应的共振频率就越高,吸声系数曲线向高频移动,且峰值增大,反射相位曲线也向高频移动,相位幅值基本不变但是跨度增大;迷宫槽宽越小,相应的共振频率就越低,吸声系数曲线向低频移动,且峰值变大,反射相位曲线也向低频移动,相位幅值不变但是跨度减小。设计了一种具有10个超表面原胞的迷宫组合结构(10个原胞除孔径外其他参数均相同),实现了从0到2π跨度上的相位调节,而且结构小巧紧凑,操作简单易行。这种结构可以进一步拓展成由多个超表面原胞构造的超薄二维阵列平面,从而实现声隐身。

A subwavelength labyrinth acoustic metasurface is proposed to effectively control the physical properties of labyrinth metasurface,and the relationship between each parameter and the acoustic metasurface is discussed in detail.The regulation mechanism of the reflected phase is analyzed emphatically,and the arbitrarily adjustment of the reflected phase is realized.To reveal the physical mechanism of the labyrinth metasurface and the relationship between each parameter and the acoustic metasurface,the influences of each tunable parameter on the sound absorption coefficient and reflected phase of the acoustic metasurface are investigated one by one.The results show that the hole diameter in the cover plate,the side length,and the groove width oflabyrinth influence the sound absorption coefficient and reflected phase,whereas the rib width of labyrinth and the plate thickness impose slight influences.Additionally,with the decrease in hole diameter,the peak absorption amplitude remains unchanged,the peak frequency has a blue shift,the reflected phase is effectively regulated by hole diameter,and the reflected phase curve shows a blue shift but the profile and trend remain unchanged.With the decrease in side length,the peak absorption coefficient increases,the peak frequency has a red shift,the reflected phase is effectively controlled by side length,the reflected phase curve shows a red shift,the phase amplitude remains unchanged,and the phase span increases.Moreover,with the decrease in groove width,the peak absorption amplitude increases,the peak frequency has a blue shift,the reflected phase is effectively manipulated by groove width,and the reflected phase curve shows a blue shift but its profile and trend remain unchanged and phase span decreases.A labyrinth structure with ten metasurface cells is designed.These ten cells have identical parameters except for hole diameter.The acoustic metasurface achieves a reflected phase regulation ranging from 0 to 2π.The compact structure is easy to operate,and it can be further expanded into an ultra-thin two-dimensional array plane constructed by metasurface cells to achieve acoustic stealth.