Porras Miguel A
Grupo de Sistemas Complejos, ETSIME, Universidad Politécnica de Madrid, Rios Rosas 21, 28003 Madrid, Spain.
Phys Rev Lett. 2019 Mar 29;122(12):123904. doi: 10.1103/PhysRevLett.122.123904.
Photons in a ring-shaped vortex light beam can have an arbitrarily high orbital angular momentum (OAM) lℏ, in addition to the spin angular momentum ±ℏ. For a pulsed vortex beam, there is, however, an upper bound to the integer units l of OAM, or topological charge of the vortex, and a lower bound to the pulse duration to carry OAM. These limits have implications in experiments with ultrashort vortices, e.g., in the generation of twisted attosecond bursts in the extreme ultraviolet, in the temporal resolution in ultrafast spectroscopy, or in the performance of OAM-based optical communications or cryptographic systems, as well as in other areas of physics as acoustics or electron waves.
除了自旋角动量±ℏ之外，环形涡旋光束中的光子可以具有任意高的轨道角动量（OAM）lℏ。然而，对于脉冲涡旋光束，OAM的整数单位l（即涡旋的拓扑电荷）存在上限，并且携带OAM的脉冲持续时间存在下限。这些限制在超短涡旋的实验中具有重要意义，例如在极紫外波段产生扭曲的阿秒脉冲串、超快光谱学中的时间分辨率、基于OAM的光通信或密码系统的性能，以及在声学或电子波等其他物理领域。
