Antireflection of optical anisotropic dielectric metasurfaces
Yu-Hsuan Liao, Wei‐Lun Hsu, Chen-Yi Yu, Chih‐Ming Wang
Abstract
Abstract We propose a hetero-nano-fin structure to further improve the efficiency of Pancharatnam–Berry phase metasurfaces. Two hetero-nano-fin types, MgF 2 /GaN and MgF 2 /Nb 2 O 5 , were investigated. The overall polarization conversion efficiency (PCE) improved from 52.7 to 54% for the MgF 2 /GaN nano-fin compared with the bare GaN nano-fin. The overall PCE of the Nb 2 O 5 nano-fin was 1.7 times higher than that of the GaN nano-fin. The overall PCE improved from 92.4% up to 96% after the application of MgF 2 antireflection. Moreover, the antireflection improves efficiency by an average of 4.3% in wavelengths from 450 to 700 nm. Although the increment of energy seems minimal, antireflection is crucial for a metasurface, not only enhancing efficiency but also reducing background signal of a meta-device.