Vortex wave and plane wave, as two most fundamental forms of wave propagation, are widely applied in various research fields. However, there is currently a lack of basic mechanism to enable arbitrary conversion between them. In this paper, we propose a new paradigm of extremely anisotropic acoustic metasurface (AM) to achieve the efficient conversion from 2D vortex waves with arbitrary orbital angular momentum (OAM) to plane waves. The underlying physics of this conversion process is ensured by the symmetry shift of AM medium parameters and the directional compensation of phase. Moreover, this novel phenomenon is further verified by analytical calculations, numerical demonstrations, and acoustic experiments, and the deflection angle and direction of the converted plane waves are qualitatively and quantitatively confirmed by a simple formula. Our work provides new possibilities for arbitrary manipulation of acoustic vortex, and holds potential applications in acoustic communication and OAM-based devices.

涡旋波和平面波作为波传播的两种最基本形式，广泛应用于各个研究领域。然而，目前缺乏基本机制来实现它们之间的任意转换。在本文中，我们提出了一种极端各向异性声学超表面（AM）的新范式，以实现从具有任意轨道角动量（OAM）的二维涡旋波到平面波的高效转换。 AM 介质参数的对称性偏移和相位的方向补偿确保了该转换过程的基本物理原理。此外，通过解析计算、数值演示和声学实验进一步验证了这一新现象，并通过简单的公式定性和定量地确定了转换后的平面波的偏转角度和方向。我们的工作为任意操纵声涡旋提供了新的可能性，并在声学通信和基于 OAM 的设备中具有潜在的应用。