Antireflection of optical anisotropic dielectric metasurfaces

We propose a hetero-nano-fin structure to further improve the efficiency of Pancharatnam-Berry phase metasurfaces. Two hetero-nano-fin types, MgF2/GaN and MgF2/Nb2O5, were investigated. The overall polarization conversion efficiency (PCE) improved from 52.7 to 54% for the MgF2/GaN nano-fin compared with the bare GaN nano-fin. The overall PCE of the Nb2O5 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 MgF2 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.

Automated summary

We propose a hetero-nano-fin structure to enhance the efficiency of Pancharatnam-Berry phase metasurfaces. Two hetero-nano-fin types, MgF2/GaN and MgF2/Nb2O5, were studied. The overall polarization conversion efficiency (PCE) of the MgF2/GaN nano-fin increased from 52.7% to 54% compared to the bare GaN nano-fin. The overall PCE of the Nb2O5 nano-fin was 1.7 times higher than that of the GaN nano-fin. The application of MgF2 antireflection improved the overall PCE from 92.4% to 96% and increased efficiency by an average of 4.3% in the wavelength range of 450 to 700 nm. Although the increment of energy seems minimal, antireflection is crucial for a metasurface to enhance efficiency and reduce background signal.