Realization of high aspect ratio metalenses by facile nanoimprint lithography using water-soluble stamps

Abstract

Nanoimprint lithography (NIL) has attracted attention recently as a promising fabrication method for dielectric metalenses owing to its low cost and high throughput, however, high aspect ratio (HAR) nanostructures are required to manipulate the full 2π phase of light. Conventional NIL using a hard-polydimethylsiloxane (h-PDMS) mold inevitably incurs shear stress on the nanostructures which is inversely proportional to the surface area parallel to the direction of detachment. Therefore, HAR structures are subjected to larger shear stresses, causing structural failure. Herein, we propose a novel wet etching NIL method with no detachment process to fabricate flawless HAR metalenses. The water-soluble replica mold is fabricated with polyvinyl alcohol (PVA) which is simpler than an h-PDMS mold, and the flexibility of the PVA mold is suitable for direct printing as its high tensile modulus allows high-resolution patterning of HAR metalenses. The diffraction-limited focusing of the printed metalenses demonstrates that it operates as an ideal lens in the visible regime. This method can potentially be used for manufacturing various nanophotonic devices that require HAR nanostructures at low cost and high throughput, facilitating commercialization.

Metasurface CGH optimization for CTIS based on interior point method

“…Instead, simulations were employed. It is noteworthy that, based on similar parameters reported in existing literature [36], this set of parameters can be feasibly implemented in practical manufacturing processes.…”

High‐Throughput Fabrication of Large‐Scale Metaholograms via One‐step Printing

“…The TiO 2 nanoparticle-embedded-resin (nano-PER) had a high refractive index and low extinction coefficient in the visible region. [11,[44][45][46] The NIL process performed using this resin formed meta-atoms composed of TiO 2 NPs on the substrate without a vacuum process. The fabricated metahologram achieved a maximum efficiency of 60.7% in blue light (𝜆 = 450 nm), suggesting that EBL, which impedes the commercialization of metaholograms, can be successfully replaced by the proposed photolithography and NIL processes.…”

Spectrally Encoded Nonscanning Imaging through a Fiber

“…In addition, this DBR-metasurface-DBR spectral filter array is suitable for miniaturization and high-volume batch manufacturing. In particular, the metasurface can be fabricated in a scalable way by nanoimprint lithography. , We emphasize that such miniaturization is of utmost importance for an application like endoscopy, which requires placing such an optical system inside a living being.…”

“…In particular, the metasurface can be fabricated in a scalable way by nanoimprint lithography. 27,28 We emphasize that such miniaturization is of utmost importance for an application like endoscopy, which requires placing such an optical system inside a living being.…”