18 August 2005 Beaming light from a subwavelength slit surrounded by an array of grooves with different depth
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In this paper, we discussed the beam focusing of light emerged from a subwavlength metallic slit surrounded by a set of grooves with constant space and width but variant depth at the exit side surface. Based on the numerical model presented by L. Martin-Moreno, F. J. Garcia-Vidal etc. (published in PRL 167401), we attempted to optimize grooves depth to obtain general beam manipulation, such as beam focusing. This attempt did not prove successful for many cases with variant focal length in our optimization practice, although some specific results display agreeable beam focusing with elongated focal depth. Further numerical computation shows that the excited electromagnetic field intensity around groove openings has a strong dependence on the groove depth, but the phase only vary with a maximum change value of π by tuning the groove depth. This property restricts greatly the modulation of electromagnetic field by just changing each groove depth. More geometrical parameters, including groove space and width, are recommended for optimization in the design of nano metallic groove and slit structures for specific beam manipulation.
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Xiangang Luo, Xiangang Luo, Changtao Wang, Changtao Wang, Chunlei Du, Chunlei Du, Haofei Shi, Haofei Shi, Hongtao Gao, Hongtao Gao, Junxian Ma, Junxian Ma, Yongqi Fu, Yongqi Fu, Haiying Li, Haiying Li, "Beaming light from a subwavelength slit surrounded by an array of grooves with different depth", Proc. SPIE 5927, Plasmonics: Metallic Nanostructures and Their Optical Properties III, 59270X (18 August 2005); doi: 10.1117/12.616306; https://doi.org/10.1117/12.616306

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