A domestic research team has implemented the world's first ultracompact spectrometer that can simultaneously analyze the color and rotation direction of light. Because this technology can replace complex optical equipment with a single chip, it has strong potential for use in a wide range of fields, including hospital diagnostic devices, environmental pollution measurement, and food safety testing.
A research team led by Professor Noh Jun-seok of the departments of mechanical engineering, chemical engineering, and electrical engineering and the graduate school of convergence at Pohang University of Science and Technology POSTECH said on the 15th that it developed a "metalens-type spectrometer" that is much smaller than existing equipment yet can determine the wavelength (color) and polarization (rotation direction) of light at once by using metasurface technology. The study was published on the 1st in the international materials journal Advanced Functional Materials.
Light contains a great deal of information. A spectrometer is a tool that analyzes light to identify the composition or state of a substance. It is used in various fields, including blood tests in hospitals, food safety tests, and measurements of air or water pollution. However, spectrometers to date have required large, complex equipment. In particular, to analyze not only the color of light but also the rotation direction (polarization) at the same time required even more equipment—like filling an entire room just to listen to a single radio.
The research team solved this with "metasurface" technology. A metasurface is a structure in which hundreds of thousands of very small pillars on the nanometer (nm, one-billionth of a meter) scale are precisely arranged. Each pillar is twisted at a specific angle, allowing free control of light.
By arranging these pillars with rotations in different directions, the team designed the device so that even light of the same color would focus at different positions depending on the polarization direction. Based on this positional information, it can simultaneously determine the color and rotation direction of light. Like a traffic officer directing cars to different roads depending on their type and direction, these tiny pillars split the light.
In practice, the team conducted experiments on four reference wavelengths (320, 370, 405, 450 nm) and observed that the focus formed at different positions depending on the direction in which the light rotated. Through this, they confirmed that color and polarization information can be measured simultaneously and accurately.
This study is significant in that it implemented, for the first time in the world, an ultracompact spectrometer that can simultaneously measure two types of information with a single device. Until now, most spectrometers smaller than a fingernail could distinguish only color, and additional equipment was needed to measure polarization.
Professor Noh said, "Applications are expected across various fields, including portable diagnostic devices, environmental sensors, and biosensing systems."
References
Advanced Functional Materials (2025), DOI: https://doi.org/10.1002/adfm.202507112