Scalable Nanoimprint Lithography Process for Manufacturing Visible Metasurfaces Composed of High Aspect Ratio TiO<sub>2</sub> Meta-Atoms

Einck, Vincent J.; Torfeh, Mahsa; McClung, Andrew; Jung, Dae Eon; Mansouree, Mahdad; Arbabi, Amir; Watkins, James J.

doi:10.1021/acsphotonics.1c00609

Cited by 77 publications

(67 citation statements)

References 50 publications

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“…Hence, the lower resolution is acceptable. Mass production of metalenses has been demonstrated by stepper/scanner lithography 53,131,[204][205][206][207][208] and nanoimprint lithography (NIL) 62,[209][210][211] technologies (Table 2), which are the most promising candidates to move metalenses from lab to fab in the future. For example, 1-cmdiameter all-glass metalenses operating at visible wavelength are manufactured using 248-nm deep-ultraviolet (DUV) projection stepper lithography 204 .…”

Section: Scaling Up and Manufacturingmentioning

confidence: 99%

“…For example, thermal NIL 212 , which is widely used, requires high pressure and temperature that easily cause damage to the template and adhesive layer. UV-NIL [209][210][211] is performed at low pressures and room temperature, minimizing magnification and distortion errors. Nevertheless, the difficultly discharged bubbles in the UV curable resist cause defects in the meta-atoms.…”

Section: Scaling Up and Manufacturingmentioning

confidence: 99%

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Dielectric metalens for miniaturized imaging systems: progress and challenges

et al. 2022

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Lightweight, miniaturized optical imaging systems are vastly anticipated in these fields of aerospace exploration, industrial vision, consumer electronics, and medical imaging. However, conventional optical techniques are intricate to downscale as refractive lenses mostly rely on phase accumulation. Metalens, composed of subwavelength nanostructures that locally control light waves, offers a disruptive path for small-scale imaging systems. Recent advances in the design and nanofabrication of dielectric metalenses have led to some high-performance practical optical systems. This review outlines the exciting developments in the aforementioned area whilst highlighting the challenges of using dielectric metalenses to replace conventional optics in miniature optical systems. After a brief introduction to the fundamental physics of dielectric metalenses, the progress and challenges in terms of the typical performances are introduced. The supplementary discussion on the common challenges hindering further development is also presented, including the limitations of the conventional design methods, difficulties in scaling up, and device integration. Furthermore, the potential approaches to address the existing challenges are also deliberated.

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Section: Scaling Up and Manufacturingmentioning

confidence: 99%

Section: Scaling Up and Manufacturingmentioning

confidence: 99%

Dielectric metalens for miniaturized imaging systems: progress and challenges

et al. 2022

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“…This will expand the handled substrate size from a chip scale to a wafer scale for further work. [ 44 ]…”

Section: Discussionmentioning

confidence: 99%

Monolithic Integration of Metalens in Silicon Photomultiplier for Improved Photodetection Efficiency

Uenoyama¹,

Ota²

2022

Advanced Optical Materials

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Improving the SiPM performance, such as photon detection efficiency (PDE) and timing resolution, is key to high-accuracy measurements for these applications.A SiPM typically contains trench areas, which are located between the boundaries surrounding SPADs, to shield from optical crosstalk. However, trenches can be photo-insensitive areas. Thus, incident photons impinging the trench areas cause PDE degradation. To solve this problem, microlenses are commonly integrated with SPADs to guide the incident photons toward their photosensitive area. [10,11] The recent trend toward miniaturization of the SPAD has led to the development of a complex photosensitive area because electrode patterns and trench areas must be formed in a limited space. However, the fabrication of complex-shaped microlenses has been challenging. Furthermore, precise alignment between microlenses and small state-of-the-art SPADs has been technically difficult because microlenses are incompatible with the CMOS process.On the other hand, metalenses, [12][13][14][15][16][17][18] such as 2D sub-wavelength structures, are highly flexible in shape and size, and can be designed to focus incident photons on the complex and small photosensitive areas of SPADs. [19,20] In addition, metalenses can be easily integrated with such SPADs without alignment errors owing to their 2D ultrathin structure and suitability for CMOS processes. Based on these advantages, we introduce a monolithic metalens integrated with SPAD rather than using microlenses.Our previous study demonstrated that metalenses can improve the PDE and timing performance of the SiPM by focusing the incident photons toward the photosensitive area of the SPAD while avoiding illumination to the trench area. [21] However, as the metalens and SiPM are spatially separated, it is difficult to fix the relative position (e.g., tilt, distance, and alignment) between the metalens and the SiPM. Thus, a separate configuration is not practical. A metalens should be monolithically integrated with its corresponding SPAD to provide good alignment and stable performance enhancement while maintaining the miniaturization and flatness of the optical device, which benefits practical applications.A 300-µm-thick support glass or protection resin is typically mounted on a SiPM to protect its surface. [22] However, when metalenses are formed on the support glass, the propagation Silicon photomultipliers (SiPMs), consisting of 2D single-photon avalanche diode (SPAD) arrays, have been widely used in many applications. In a SiPM, trench structures surround every SPAD to minimize optical crosstalk; however, these structures are photo-insensitive areas. The previous study revealed that the use of metalenses for focusing incident photons on the photosensitive area of SPADs effectively improves the SiPM performance. However, ensuring good alignment between the metalens and SiPM has been difficult owing to its separated configuration. Herein the authors report the monolithic integration of a metalens with SPAD to provide stable pho...

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“…[ 44 ] It is partially due to the difficulty in fabricating low loss materials and demonstrating ground‐breaking applications such as “perfect lens”, and, meanwhile, “metalens” consisting of millions of meta‐atoms with nanoimprint lithography process has been successfully demonstrated and commercialized. [ 45 ] Another cornerstone of metamaterial research is “transformation optics”, a.k.a. “coordinate transformation”, where the concept of “cloaking [ 46 ] ” has drawn significant attention from the public and academic community.…”

Section: Clustering Abstractmentioning

confidence: 99%

The Dawn of Metamaterial Engineering Predicted via Hyperdimensional Keyword Pool and Memory Learning

Cha

Hao

2022

Advanced Optical Materials

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Metamaterials research has been ongoing for more than 20 years and it has gained much public and scientific interest. There have been many experts forecasting on the road ahead for metamaterials, notably, in lieu of “knowledge tree” in 2010. Ten years on, it is proposed to re‐examine these claims by using automated computer tools, such as natural language processing (NLP), to extract research information for processing and analyzing from unstructured texts in publications. In this study, a fully auto‐generated database of 43 678 abstracts related to metamaterials published between 2000 and 2021 using Scopus Search API (Application Programming Interface) is built. Applying word embedding, each keyword is studied in a hyperdimensional vector space and clusters so that their relationships can be visualized for assessing the popularity and trends of research themes. A neural network model developed based on the encoder–decoder long short‐term memory (LSTM) architecture is finally trained to predict future directions and theme evolutions in the next four years for selected topics. This study not only provides vital information in terms of impact of metamaterials research but also lays down a solid foundation for the development of future metamaterial research roadmap in the form of Gartner hype cycle.

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

Cited by 77 publications

References 50 publications

Dielectric metalens for miniaturized imaging systems: progress and challenges

Dielectric metalens for miniaturized imaging systems: progress and challenges

Monolithic Integration of Metalens in Silicon Photomultiplier for Improved Photodetection Efficiency

The Dawn of Metamaterial Engineering Predicted via Hyperdimensional Keyword Pool and Memory Learning

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

Cited by 77 publications

References 50 publications

Dielectric metalens for miniaturized imaging systems: progress and challenges

Dielectric metalens for miniaturized imaging systems: progress and challenges

Monolithic Integration of Metalens in Silicon Photomultiplier for Improved Photodetection Efficiency

The Dawn of Metamaterial Engineering Predicted via Hyperdimensional Keyword Pool and Memory Learning

Contact Info

Product

Resources

About

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