Research team from POSTECH, Korea University, and Samsung Electronics: More than hair
Development of 100x Thinner Metalens and Mass Production Technology


Could smartphone cataracts disappear?

The Ministry of Science and ICT announced on the 2nd that the research team of Professor Noh Jun-seok of the Department of Mechanical Engineering/Department of Chemical Engineering at Pohang University of Science and Technology, together with the research team of Professor Lee Heon of the Department of New Materials Engineering at Korea University and Master Han Seung-hoon of the Imaging Device Lab at Samsung Advanced Institute of Technology, developed an infrared ultra-thin lens that maintains the performance of existing refractive lenses but is 10,000 times thinner, as well as the technology to mass-produce it.

Conventional refractive lenses are large and heavy, and their performance deteriorates as their size decreases. Smartphone cameras use composite lenses composed of eight or nine refractive lenses to reduce image distortion. However, the difficulty in reducing the thickness of these composite lenses leads to the camera protruding from the back of the smartphone.

Researchers have been exploring metamaterial-based lenses to develop high-performance, yet compact lenses. Metamaterials offer the ability to freely control a variety of optical properties, including negative and ultra-high refractive indices, that conventional materials cannot achieve. This allows for the creation of unprecedented optical devices, such as ultra-thin flat lenses, high-resolution holograms, and invisibility cloaks. This has led to extensive research worldwide.

However, the electron beam lithography process used to produce metamaterials is slow and expensive, so the unit price of metamaterials produced through it is also high. To overcome this, the research team succeeded in developing a nano-composite-based nano-molding material that has optical properties suitable for implementing metamaterials and can be freely shaped, as well as a one-step printing technology that can shape it in a single process.

Nano-molded materials are made by mixing nanoparticles with a photosensitive resin, which normally exists in a liquid state but hardens into a hard plastic when exposed to light. This allows for a wide range of control over the optical properties of the nano-molded materials, depending on the type and concentration of nanoparticles. This allows them to replace existing materials commonly used in the production of metamaterials. Furthermore, their unit cost is lower than that of existing materials, making them highly cost-effective.

A new one-step printing technology for nanomaterials can produce metamaterials more than 100 times faster than conventional electron beam lithography. Additionally, metamaterials can be implemented on curved and flexible substrates that are difficult to be compatible with existing processes, making it possible to apply them to wearable devices.

The research team developed an ultra-thin metalens with a thickness of 1 ㎛ (micrometer), which is more than 100 times thinner than the thickness of a human hair, based on silicon nanocomposites and printing technology. They successfully combined this with an actual optical system to achieve imaging, verifying the practical applicability of the research results.

Professor Noh Jun-seok said, “The ultra-thin metalens is 10,000 times thinner than existing infrared refractive lenses with the same optical properties, so it can solve various problems caused by large and heavy refractive lenses. In the future, it is expected to be applied to various fields such as infrared endoscopes, CCTV, and night vision goggles.”

Meanwhile, the results of this study were published in the world-renowned academic journal ACS Nano on January 1, 2021, under the title 'Printable Nanocomposite Metalens for High-Contrast Near-Infrared Imaging.'