Shen Yijie, Fu Xing, Gong Mali
Opt Express. 2018 Oct 1;26(20):25545-25557. doi: 10.1364/OE.26.025545.
We report, for the first time to the best of our knowledge, a truncated diffraction with a triangular aperture of the SU(2) geometric modes and propose a method to detect the complicated orbital angular momentum (OAM) of an SU(2) wave-packet. As a special vortex beam, a nonplanar SU(2) mode carrying special intensity and OAM distributions brings exotic patterns in a truncated diffraction lattice. A meshy structure is unveiled therein by adjusting the illuminated aperture in the vicinity of the partial OAM regions, which can be elaborately used to evaluate the partial topological charge and OAM of an SU(2) wave-packet by counting the dark holes in the mesh. Moreover, through controlling the size and position of the aperture at the center region, the truncated triangular lattice can be close to the classical spot-array lattice for measuring the center OAM. These effects being fully validated by theoretical simulations greatly extend the versatility of topological structures detecting special beams.
据我们所知，我们首次报道了具有SU(2)几何模式三角形孔径的截断衍射，并提出了一种检测SU(2)波包复杂轨道角动量（OAM）的方法。作为一种特殊的涡旋光束，携带特殊强度和OAM分布的非平面SU(2)模式在截断衍射晶格中带来奇特图案。通过在部分OAM区域附近调整照明孔径，其中揭示了一种网状结构，通过计算网格中的暗孔，可以精心地利用该网状结构来评估SU(2)波包的部分拓扑电荷和OAM。此外，通过控制中心区域孔径的大小和位置，截断的三角形晶格可以接近用于测量中心OAM的经典光斑阵列晶格。这些效应通过理论模拟得到充分验证，极大地扩展了检测特殊光束的拓扑结构的多功能性。
