IEEE Access (Jan 2021)
Analysis of OAM Performance Using Metalenses of Different Resolutions
Abstract
Recently, metasurfaces have been extensively studied, especially in connection with the construction of orbital angular momentum (OAM)-carrying beams. However, the dependence of OAM performance on the resolution of unit cells remains to be investigated. In this paper, 27 types of metalenses of varying phase resolutions (1-bit, 2-bit, and 3-bit) and with unit cells of varying width resolutions ( $1\lambda _{0}$ , (1/2) $\lambda _{0}$ , and (1/3) $\lambda _{0}$ ) were designed to analyze this dependence via simulation. A thorough analysis of the simulated results, including the radiation pattern, the near-field amplitude, the near-field phase, and the OAM mode purity, revealed that the OAM performance of a metalens improves with an increase in resolution. In addition, even metalenses of 1-bit phase resolution and $1\lambda _{0}$ width resolution were observed to exhibit OAM mode purities higher than 88%. We expect the conclusions of this study to be useful as guidelines during the future design of OAM metalenses or metasurfaces.
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