用于产生和传输涡旋光束的微结构光纤设计及制造技术研究

项目名称： 用于产生和传输涡旋光束的微结构光纤设计及制造技术研究

项目编号： No.11474351

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 王丽莉

作者单位： 中国科学院西安光学精密机械研究所

项目金额： 100万元

中文摘要： 具有特殊螺旋波前结构和光子轨道角动量的涡旋光束，在新一代光通信技术及量子信息传输、成像新技术等领域的应用前景十分广阔。本申请针对我国开展涡旋光纤新技术研究急需的关键纤维光学材料开展研究工作。拟设计并制造两种基于微结构的涡旋光纤。一种是能够将圆偏振高斯光束转换成涡旋光束，具有方形内芯和环形外芯结构的微结构光纤。方形芯设计可以打破波导的圆对称结构，使输入方芯中的圆偏振基模可以被耦合到环形芯区，借助于自旋角动量和轨道角动量间的转移，产生涡旋束。另一种是能够高效传输自旋相反的圆偏振高斯模和不同拓扑荷的涡旋光束，具有圆形内芯和环形外芯结构的微结构光纤。圆形芯可以传输两种自旋相反的圆偏振光，而环形芯区传输拓扑荷为±1的涡旋束。采用微结构设计，可以消除因多种材料热学、力学性质的差异，导致的大尺寸预制棒难以制备的弊端，使涡旋光纤制造更容易实现规模化制造。本申请提出的两种微结构涡旋光纤，未见国内外报道。

中文关键词： 涡旋光束；产生/传输；微结构光纤；设计；制造

英文摘要： The data-carring capacity of single-mode optical fibers has increased by four orders of magnitude in the past three decades, primarily because of multilplexing techniques that use wavelength, phase, and polarization of light to encode information. As the capacity of the current optical fiber systems reaches limits imposed by nonlinear effects，the possibility of spatial-division- multilplexing methods by use of multicore and multimodes fibers emerged to address the forthcoming capacity crunch. Although multicore fibers and potentially require more complex manufacturing than do circularly symmetric multimode fibers, conventional multimode fibers suffer from mode coupling caused by random perturbation in fiber. Methods that have been developed to address the problem of mode coupling so far have been dependent on computationally intensive digital signal processing algorithms, and have been based either on adaptive optics feedback or complex multiple-input multiple-output methodologies. Recently,prof.Siddharth Ramachandran in Boston University, Prof.Alan E. Willner1in University of Southern California, and Moshe Tur in Tel Aviv University proposed and demonstrated muxing, transmission and demuxing of 2 orbital angular Momentum beams over 10 wavelength channels through 1.1-km of vortex fiber. An aggregated total capacity of 1.6-Tbit/s is achieved by using 20-Gbaud/s 16-QAM signal on each channel. One of the key technologies for OAM-based new fiber communication is structure design and fabirication technique of a new type fiber,named vortex fiber. We will design and fabricate a kind of microstructured fiber structures,with a square core and ring refractive index profile that converts an input circular polarized Gaussian mode into optical orbital angular momentum (OAM) modes. By breaking the circular symmetry of the waveguide, the input circularly polarized fundamental mode in the square core can be coupled into the ring region to generate higher-order OAM modes, corresponding to the transference of spin angular momentum and orbital angular momentum. We will also design and fabricate another kind of microstructured optical fiber with a step-index central core and a annular high-index profile.The annular high-index profile that we expect to help with mode stability. the step-index central core,does not detract from the design philosophy, instead it allows for the fundamental mode to be Gaussian shaped, enabling low-loss coupling, either from free-space lasers or conventional single-mode fibers. Here,proposed microstructured fibers will open the door to exploiting microstructured fiber to generate and transmite vortex beams. The fabrication method for the microstructured vortex fiber has many merits such as only using one materials,big size preform,suitable to mass-fabrication and so on.

英文关键词： vortex beams;generation/propagating;microstructured optical fiber;design;fabrication