Large-area optical metasurface fabrication using nanostencil lithography

Area of Science:

• Materials Science and Engineering
• Optics and Photonics

Background:

• Optical metasurfaces offer advanced light manipulation capabilities.
• Existing fabrication methods often face challenges in scalability, yield, and resolution.

Purpose of the Study:

• To demonstrate a large-area fabrication process for optical metasurfaces.
• To improve the yield and reliability of nanostencil fabrication.
• To achieve high-performance meta-lenses using the developed technique.

Main Methods:

• Utilized reusable silicon nitride (SiN) on silicon (Si) nanostencils for metasurface fabrication.
• Partially etched the front-side SiN layer to transfer patterns and preserve membrane integrity during etching.
• Employed a sacrificial resist layer to control the nanostencil-substrate gap for enhanced liftoff.

Main Results:

• Fabricated 1.5 mm diameter PbTe meta-lenses on CaF2 with diffraction-limited focusing.
• Achieved focusing efficiencies of 42% (2 mm focal length) and 53% (4 mm focal length).
• Demonstrated the reusability of nanostencils through chemical cleaning.

Conclusions:

• The developed nanostencil fabrication process is scalable and improves yield for optical metasurfaces.
• Reusable SiN nanostencils enable reliable and high-resolution fabrication of high-performance meta-lenses.
• This technique provides a viable pathway for the mass production of advanced optical components.