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| 具有亚波长结构的突然自聚焦光束的频谱调控研究 |
| Spatial spectrum modulation for abruptly autofocusing beams with subwavelength structures |
| 投稿时间：2020-11-09 |
| DOI：10.3969/j.issn.1005-5630.2021.04.010 |
| 中文关键词: 太赫兹 突然自聚焦 高通滤波 带通滤波 傅里叶空间 |
| 英文关键词:terahertz abruptly autofocusing high-pass filter band-pass filter Fourier space |
| 基金项目:金属纳米线阵列超材料的空间非局域光学特性机理研究（16ZR1446000） |
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| 中文摘要: |
| 为了提高具有亚波长结构的圆对称艾里光束的自聚焦特性，将光束的工作波长扩大至太赫兹波段，并在频谱空间中分别加入高通和带通滤波进行调控。对两种滤波效果进行对比发现，通过滤波函数的参数变化可以控制空间频谱的分布，从而对光束的传播特性进行调制。当选取合适的参数时，焦斑尺寸减小，焦点强度增加，突然自聚焦特性会大幅增强，同时可实现焦点位置的控制。比较两种调制方法后发现，带通滤波后的光束拥有更好的自聚焦特性。 |
| 英文摘要: |
| In order to improve the autofocusing property of circular Airy beam with subwavelength structures, the working wavelength of the beam is expanded to terahertz band. This paper studies the propagation properties of the terahertz circular Airy beam by high-pass and band-pass filtering in Fourier space. It is found that the parameter changes of the high-pass and band-pass functions can control the distribution of the spatial frequency spectrum. Thus, the propagation characteristics of the beam are modulated. When the parameters are chosen appropriately, the size of focal spot is reduced, the maximum focal intensity and especially the abruptly autofocusing property could be greatly enhanced. Meanwhile, the focal position can be controlled. Compared with the high-pass filtering, the beam after the band-pass filtering has better abruptly autofocusing characteristics. |
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