Busan National University Professor Kim Gyu-jeong's Team Develops Nanopixels for Freely Controllable Colors Using Polarization

Inducing Various Optical Property Changes by Adjusting Distance Between Structures... Innovation in Optical Security and Displays
Color Conversion Achievable Over a Wavelength Range of Up to Several Hundred Nanometers, Realizing 3.2 Times Higher Contrast in On-Off Light Intensity

A research team at Pusan National University has developed nanopixels that can freely implement color conversion and on-off modes according to polarization (the phenomenon where the electric or magnetic field constituting an electromagnetic wave vibrates in a specific direction as it propagates). This development is expected to have diverse applications in future promising technologies, including optical security and encrypted images, data storage, and displays.

Pusan National University (President Choi Jae-won) announced on the 20th that Professor Kim Kyu-jung’s research team from the Department of Optical Mechatronics Engineering successfully developed nanopixels capable of inducing various optical property changes depending on polarization, achieving free color conversion and on-off mode implementation.

The Pusan National University research team diversified the optical properties expressed according to polarization by utilizing the inherent structural characteristics (shape and size) of the nanostructures constituting the plasmonic metasurface nanopixels and the distance characteristics between nanostructures in a pair of nanodisks forming a single nanopixel. Through this, they induced control over various optical properties such as saturation, brightness, and hue in fixed-form nanopixels.

As a result, they were able to adjust color conversion over a wavelength range of up to several hundred nanometers, and in the on-off mode, they realized a contrast in light intensity approximately 3.2 times higher.

The ‘plasmonic metasurface’ is an ultrathin artificial structure developed to precisely control light. This surface is composed of metallic nanostructures, and when interacting with light of a specific wavelength, a phenomenon called localized surface plasmon resonance (LSPR) occurs on the metal surface. This allows for extremely precise control of light reflection, refraction, absorption, polarization, phase, and more. It has been actively researched recently due to its rich applicability and versatility in fields such as electrical and electronic engineering, chemistry, bio-medicine, and pharmacology.

The optical properties of plasmonic meta-structures are determined by the structural characteristics of the structure itself, materials, and the optical properties of the surrounding environment. Modulation of optical properties is possible through changes in these factors. This approach changes optical properties such as absorption, reflection, transmission, and scattering, and is utilized in various fields including optical filters, optical printing, surface-enhanced Raman scattering (SERS) sensors, high-sensitivity optical sensors, and high-resolution imaging.

Professor Kim Kyu-jung’s team at Pusan National University has actively conducted research in this field, publishing over 80 related papers and presenting at international conferences.

The polarization-dependent optical property modulation method of the nanopixels proposed in this study successfully implements nanopixels expressing various modes with fixed-form nanostructures that minimize physical degradation of components. These can be applied in displays, optical devices, high-sensitivity optical sensors, data security and encryption, and data storage.

In particular, the significance lies in developing nanopixels capable of expressing the optical properties of unique nanostructures, inducing optical property changes according to polarization, and implementing on-off modes. The ability to determine the range of optical property changes caused by polarization through structural characteristic control and to express intentional discrete states within that range also enhances the research value.

Professor Kim Kyu-jung (corresponding author) of Pusan National University said, “The nanopixels developed this time can extend the modulation range of optical property expression not only in the visible light region but also into the near-infrared region. The range of optical modulation, color conversion, and on-off modes can be controlled as intended, which is particularly significant. This has great future high added-value industrial potential and a wide range of applications, raising its research value. We expect continuous research achievements in this field going forward.”

This research achievement was reported in a paper titled ‘Polarization-Sensitive Subwavelength Nanopixel for On-Off and Color Switchable Color Printing’ and was recently published on January 8 in the international academic journal Advanced Optical Materials.

This research was supported by the Ministry of Education’s Science and Engineering Academic Research Support Project (Postdoctoral Domestic Training), the Ministry of Science and ICT’s Excellent Researcher Exchange Support Project (BrainLink), and the Future Defense Innovation Technology Development Project. It was conducted by Professor Kim Kyu-jung (corresponding author) of the Department of Optical Mechatronics Engineering at Pusan National University, Dr. Song Hye-rin (first author) and Dr. Ahn Hee-sang (co-author) from the Nano-Bio Convergence Research Institute.

From the left: Professor Kim Gyu-jeong, Dr. Song Hye-rin, Dr. Ahn Hee-sang. Provided by Pusan National University

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