Scalable Nanoimprint Lithography Process for Manufacturing Visible Metasurfaces Composed of High Aspect Ratio TiO2 Meta-Atoms

By Vincent J. Einck, M. Torfeh, A. McClung, D. Jung, M. Mansouree, Amir Arbabi, J. Watkins. ACS Photonics, 2021

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: We report a one-step additive manufacturing process to fabricate metalenses for visible wavelengths. Nanostruc-tures with aspect ratios larger than eight and critical dimensions smaller than 60 nm were produced using nanoimprint lithography and a titanium dioxide nanocrystal-based imprint material, resulting in inorganic structures exhibiting a refractive index of n = 1.9. As a demonstration, we fabricate metalenses with numerical apertures (NAs) of 0.2 and focusing e ffi ciencies over 50%. Manufacturability was assessed by performing 15 manual imprints in 30 min (2 min of process time per imprint) with a single stamp. All imprinted lenses exhibit comparable performance, paving the way for high-throughput and low-cost manufacturing of fl at optical devices. Metalenses with a diameter of 4 mm were also fabricated to investigate the success of large area replication using this process, showing e ffi ciencies of 43%, indicating good macroscopic imprinting.

Subfields: Atomic and Molecular Physics, and Optics, Biomedical Engineering, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/d95d764f466c9f1a46a5c9165a3af4a25de833ab