In this paper, a new method to generate dark hollow beam (DHB) was introduced. The method is based on a special fiber with three-layer step-index structure and the technique of long period fiber grating (LPFG). The working wavelength depends on the parameters of the special fiber. The wavelength of 532 nm was applied in the application described in this article. High quality DHBs were generated in the experiments. Several experimental results have been shown to demonstrate the influences of grating pitch of LPFG. Methods to improve the quality of DHB were discussed.

中文翻译：

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基于特殊光纤和长周期光纤光栅的暗中空光束发生器

本文介绍了一种产生暗空心光束（DHB）的新方法。该方法基于具有三层阶跃折射率结构的特殊光纤和长周期光纤光栅（LPFG）技术。工作波长取决于特殊光纤的参数。在本文描述的应用中应用了532 nm的波长。在实验中生成了高质量的DHB。几个实验结果已经表明了LPFG光栅间距的影响。讨论了提高DHB质量的方法。