Reflective metalens with an enhanced off-axis focusing performance

Area of Science:

• Optics and Photonics
• Metasurface Technology
• Nanophotonics

Background:

• Metalenses are advanced optical components with significant potential in metasurface applications.
• All-dielectric reflective metalenses are less explored, particularly concerning their off-axis performance.
• Existing metalenses often rely on metallic components, limiting their efficiency and integration capabilities.

Purpose of the Study:

• To propose and experimentally investigate an all-dielectric reflective metalens.
• To evaluate the off-axis focusing performance of the novel metalens design.
• To demonstrate high reflectivity and efficiency for visible light applications.

Main Methods:

• Experimental characterization of titanium dioxide (TiO2) and silicon dioxide (SiO2) optical properties.
• Design of a reflective metalens utilizing a modified parabolic phase profile.
• Integration of the metalens onto a dielectric distributed Bragg reflector (DBR) structure with five dielectric pairs.
• Experimental analysis of focusing efficiency for incident beam angles from 0° to 30°.

Main Results:

• The proposed reflective metalens operates at a visible wavelength of 0.633 µm.
• The device achieves high reflectivity due to the integrated dielectric DBR structure.
• Focusing efficiency remains above 54% for incident angles up to 30°, outperforming conventional designs.

Conclusions:

• The developed all-dielectric reflective metalens offers superior off-axis focusing performance.
• The high efficiency and reflectivity make it a strong candidate for photonic miniaturization and integration.
• This work advances the field of metasurfaces and all-dielectric optical components.