Theoretical analysis and design guideline for focusing subwavelength gratings

We propose a planar dielectric reflector with focusing ability using concentric circular subwavelength gratings (CC-SWGs). The two-dimensional focusing ability of CC-SWGs is investigated by the rigorous coupled-wave analysis (RCWA) and finite element method (FEM). By designing the concentric circula...

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Bibliographic Details
Published inOptics express Vol. 23; no. 3; pp. 2639 - 2646
Main Authors Duan, Xiaofeng, Zhou, Guren, Huang, Yongqing, Shang, Yufeng, Ren, Xiaomin
Format Journal Article
LanguageEnglish
Published United States 09.02.2015
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Summary:We propose a planar dielectric reflector with focusing ability using concentric circular subwavelength gratings (CC-SWGs). The two-dimensional focusing ability of CC-SWGs is investigated by the rigorous coupled-wave analysis (RCWA) and finite element method (FEM). By designing the concentric circular pattern of the grating surface, a focusing reflector with high numerical aperture (NA) and high reflectivity is constructed. A CC-SWG reflector with a diameter of 32.6μm and a focal length of 6μm is investigated, which exhibits high focusing ability at normal incidence with a radially polarized plane wave. At the reflection focal plane, the full-width-half-maximum (FWHM) of the electric field intensity is 0.89μm. Numerical aperture value as high as 0.93 is achieved for the reflector with very high reflectivity of 92%.
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content type line 23
ISSN:1094-4087
1094-4087
DOI:10.1364/oe.23.002639