A hybrid achromatic metalens.

Area of Science:

• Optics and Photonics
• Nanotechnology
• Materials Science

Background:

• Metalenses are ultra-thin optical elements utilizing subwavelength structures for light manipulation.
• Traditional metalenses correcting chromatic aberration often exhibit reduced focusing efficiency.
• Existing metalenses offer advantages in size, weight, and functionality like polarization control.

Purpose of the Study:

• To introduce a novel Hybrid Achromatic Metalens (HAML) design.
• To overcome the trade-off between chromatic aberration correction and focusing efficiency in metalenses.
• To achieve high focusing efficiency over a broad wavelength range (1000-1800 nm).

Main Methods:

• Developed a design methodology combining recursive ray-tracing and simulated phase libraries.
• Avoided computationally intensive global search algorithms for metalens design.
• Fabricated HAMLs using multi-photon lithography for customization and molding for mass production in low-refractive index materials.

Main Results:

• Achieved diffraction-limited performance for numerical apertures of 0.27, 0.11, and 0.06.
• Demonstrated average focusing efficiencies greater than 60%, with maximum efficiencies reaching 80%.
• Introduced an air-spaced HAML design for larger diameters and numerical apertures.

Conclusions:

• The Hybrid Achromatic Metalens (HAML) effectively corrects chromatic aberration with high focusing efficiency.
• HAMLs offer a viable solution for advanced optical systems requiring compact and efficient achromatic focusing.
• The fabrication methods allow for both customized and mass-produced metalens solutions.