In this article, an all-fiber super-variable focusing vortex beam generator is proposed and demonstrated, the focal point of which can be drastically relocated by varying the wavelength of the incident light. The all-fiber generator is fabricated by etching a spiral zone plate (SZP) on the top of the composite fiber structure composed of a single mode fiber and a quarter pitch graded index fiber using focused ion beam lithography. Numerical simulation and experimental measurements have been applied in investigation of all-fiber output light field characteristics, such as the focal spot, focal length, and vortex topological charges. Results show that these parameters can be controlled by flexibly adjusting the design parameters of SZP microstructure. In particular, the position of the donut-shaped focus spot can be dynamically tuned in a wide range by varying the incident laser wavelength with the focal spot profile remains constant. The all-fiber generator can be potentially applied in particle manipulation, high capacity communication, and fiber optic endoscopic imaging, all of which require ultra-compact, multi-dimension, and flexible focusing schemes.

中文翻译：

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基于光纤刻蚀螺旋波带板的超变聚焦涡旋光束发生器


在本文中，提出并演示了一种全光纤超可变聚焦涡旋光束发生器，其焦点可以通过改变入射光的波长来彻底重新定位。全光纤发生器是通过使用聚焦离子束光刻在由单模光纤和四分之一节距渐变折射率光纤组成的复合光纤结构的顶部蚀刻螺旋波带片（SZP）来制造的。数值模拟和实验测量已应用于全光纤输出光场特性的研究，例如焦斑、焦距和涡旋拓扑电荷。结果表明，这些参数可以通过灵活调整SZP微观结构的设计参数来控制。特别是，通过改变入射激光波长，可以在宽范围内动态调整环形焦点的位置，同时焦点轮廓保持不变。全光纤发生器可潜在应用于粒子操纵、高容量通信和光纤内窥镜成像，所有这些都需要超紧凑、多维度和灵活的聚焦方案。