Lei Sihong, Xia Shiqi, Song Daohong, Xu Jingjun, Buljan Hrvoje, Chen Zhigang
The MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin, China.
Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, China.
Nat Commun. 2024 Sep 3;15(1):7693. doi: 10.1038/s41467-024-52070-6.
Robust high-order optical vortices are much in demand for applications in optical manipulation, optical communications, quantum entanglement and quantum computing. However, in numerous experimental settings, a controlled generation of optical vortices with arbitrary orbital angular momentum remains a challenge. Here, we present a concept of "optical vortex ladder" for the stepwise generation of optical vortices through Sisyphus pumping of pseudospin modes in photonic graphene. The ladder is applicable in various lattices with Dirac-like structures. Instead of conical diffraction and incomplete pseudospin conversion under conventional Gaussian beam excitations, the vortices produced in the ladder arise from non-trivial topology and feature diffraction-free Bessel profiles, thanks to the refined excitation of the ring spectrum around the Dirac cones. By employing a periodic "kick" to the photonic graphene, effectively inducing the Sisyphus pumping, the ladder enables tunable generation of optical vortices of any order even when the initial excitation does not involve any orbital angular momentum. The optical vortex ladder stands out as an intriguing non-Hermitian dynamical system, and, among other possibilities, opens a pathway for applications of topological singularities in beam shaping and wavefront engineering.
在光学操纵、光通信、量子纠缠和量子计算等应用中，对稳健的高阶光学涡旋有很大需求。然而，在众多实验环境中，可控地产生具有任意轨道角动量的光学涡旋仍然是一个挑战。在此，我们提出一种“光学涡旋阶梯”的概念，用于通过在光子石墨烯中对赝自旋模式进行西西弗斯泵浦来逐步产生光学涡旋。该阶梯适用于各种具有类狄拉克结构的晶格。与传统高斯光束激发下的锥形衍射和不完全赝自旋转换不同，阶梯中产生的涡旋源于非平凡拓扑结构，并具有无衍射的贝塞尔分布，这得益于对狄拉克锥周围环形光谱的精细激发。通过对光子石墨烯施加周期性“踢”，有效地诱导西西弗斯泵浦，即使初始激发不涉及任何轨道角动量，该阶梯也能实现任意阶光学涡旋的可调谐产生。光学涡旋阶梯作为一个引人入胜的非厄米动力学系统脱颖而出，并且在其他可能性中，为拓扑奇点在光束整形和波前工程中的应用开辟了一条途径。
