Abstract

This study proposes a Fibonacci subwavelength circular grating (FiSCG) arranged with Au concentric annuli. The numerical results show that, when illuminated by radially polarized light with a wavelength of 632.8 nm, four foci can be observed in the non-near-field with full width at half-maximum (FWHM) of $0.378\lambda$, $0.421\lambda$, $0.520\lambda$, and $0.496\lambda$, respectively. These possess low sidelobe intensity. Moreover, FiSCG achieves non-near-field sub-diffraction focusing in the visible wavelength range by varying the widths of the air slit and the Au ring. The ratio of the widths and the incident wavelength is about 0.4. This finding provides a wider applied range for FiSCG and a reference for the research on Fibonacci-arranged structures.

© 2018 Optical Society of America

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