The orbital angular momentum (OAM) of light has been shown to be useful in diverse fields ranging from astronomy and optical trapping to optical communications and data storage. However, one of the primary impediments preventing such applications from widespread adoption is the lack of a straightforward and dynamic method to sort incident OAM states without altering the states. Here, we report a technique that can dynamically filter individual OAM states and preserve the incident OAM states for subsequent processing. Although the working principle of this technique is based on resonance, the device operation is not limited to a particular wavelength. OAM states with different wavelengths can resonate in the resonator without any additional modulation other than changing the length of the cavity. Consequently, we are able to demonstrate a reconfigurable OAM sorter that is constructed by cascading such optical resonators. This approach does not require specially designed components and is readily amenable to integration into potential applications.

光的轨道角动量（OAM）已被证明可用于从天文学和光捕获到光通信和数据存储等各个领域。然而，阻止此类应用程序广泛采用的主要障碍之一是缺乏一种直接且动态的方法来对事件 OAM 状态进行排序而不改变状态。在这里，我们报告了一种可以动态过滤各个 OAM 状态并保留事件 OAM 状态以供后续处理的技术。尽管该技术的工作原理基于共振，但设备操作并不限于特定波长。不同波长的OAM态可以在谐振器中谐振，除了改变腔的长度之外，无需任何额外的调制。因此，我们能够展示一种通过级联此类光学谐振器构建的可重构 OAM 分类器。这种方法不需要专门设计的组件，并且很容易集成到潜在的应用中。