Simulation Studies on Defect-induced Performance Degradation of Dielectric Metalenses for Visible Wavelengths

초록

Dielectric metalenses focus light via the well-controlled phase delay of transmitted light through individual dielectric resonators. At visible wavelengths, the resonators generally possess extremely high height-to-width aspect ratio to compensate for the relatively low refractive indices of commonly used dielectrics. Such structures are difficult to fabricate and prone to mechanical fractures, the effects of which must be considered for realistic applications. In this study, we investigate the performance of metalenses comprising TiO2 nanopillars with two common types of defects – randomness of pillars’ radii and mechanical fracture of pillars. We first systematically investigate the effect of defects on the transmission properties of an individual pillar and then observe the collective performance degradation of the whole metalens under various circumstances. In both cases, we find that defects significantly affect the collection efficiency but only slightly change the focal spot size. We also discuss potential means to mitigate the effect of realistic defects. © 2022 The Korean Physical Society. All rights reserved.

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