The hollow flat-topped Gaussian beam (HFTGB) is proposed to describe the flat light ring beams. The analytical formula for the propagation of HFTGB through any ABCD system is obtained based on the expansion of hollow Gaussian beams. Based upon this formula, the propagation characteristics of HFTGB are investigated in detail. It is found that both 3D bright spot and dark spot exist in the propagating process, and a perfect optical cage could be created by choosing special parameters. Finally, the HFTGBs are generated in experiment, and the modulation methods for the optical cage are proved.

中文翻译：

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空心平顶高斯光束的传播特性及其在产生光笼中的应用

提出了空心平顶高斯光束（HFTGB）来描述扁平环形光束。HFTGB 在任何 ABCD 系统中传播的解析公式是基于空心高斯光束的扩展获得的。基于该公式，详细研究了HFTGB的传播特性。发现在传播过程中同时存在3D亮点和暗点，通过选择特殊的参数可以创建一个完美的光笼。最后在实验中生成了 HFTGBs，并证明了光笼的调制方法。