Researchers successfully mass-produce metalenses for visible light, opening new possibilities for optics

Metalenses, a promising solution to the camera bumps on smartphones, have garnered significant attention in the scientific community. However, their precise production and high cost have posed challenges for scalable manufacturing. Despite these obstacles, a team of researchers led by Professor Junsuk Rho from POSTECH has achieved a groundbreaking feat by successfully mass-producing metalenses for visible light—the first-ever recorded. The team’s study, which was recently published in Nature Materials, also featured the contributions of other researchers from Korea University and the Research Institute of Industrial Science and Technology (RIST).

To overcome the limitations of the production process, the team combined photolithography and nanoimprint lithography—two techniques utilized in semiconductor and display manufacturing. Photolithography patterns a substrate using light, while nanoimprint lithography prints patterns onto a substrate using a stamp with nano-sized patterns.

The research team utilized electron beam lithography to create a single pattern, which they replicated via deep-ultraviolet ArF photolithography to develop a 12-inch master stamp. Using this stamp alongside nanoimprint lithography, they achieved high-speed production of metalenses measuring 1 cm in diameter.

Traditional nanoscale structures made with nanoimprint technology have had low refractive indices and low efficiency, necessitating expensive means to enhance efficiency. However, the research team managed to improve the metalenses’ efficiency up to 90% by applying a 20-nanometer-thick coating of titanium dioxide (TiO2). By combining these two technologies, they were able to mass-produce lightweight, high-performance metalenses using a straightforward process.

The researchers also showcased the metalenses’ practical applications by constructing a VR device that displayed images in red, green, and blue. This study marks the inaugural project of the POSCO-POSTECH-RIST Convergence Research Institute and brings the commercialization of metalenses one step closer. POSCO anticipates that this breakthrough will enable the company’s transition from a steel manufacturer to a futuristic materials enterprise.

Lead researcher Professor Junsuk Rho shared his thoughts on the research, stating that it could transform meta-material research, which has remained in the experimental stage for over two decades, into an industrial application with practical real-life use. The team’s accomplishment in mass-producing metalenses for visible light on a wafer scale positions them as world leaders in advanced technology.

Source: Pohang University of Science and Technology

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