□ A research team led by Professor Jiwoong Yang of the Department of Energy Science and Engineering at DGIST (President Kunwoo Lee) has developed next-generation optical sensor technology capable of precisely detecting not only the intensity and wavelength of light but also its rotational direction—the spin information of photons. The team successfully implemented a quantum-dot-based optical sensor that can detect “circularly polarized light (CPL)” across an ultra-wide spectral range—from ultraviolet to short-wave infrared—demonstrating photodetection performance comparable to that of commercial silicon optical sensors.
□ CPL refers to light in which the electric field rotates helically as it propagates. This is directly linked to the spin information of photons—the fundamental particles of light. This polarization information serves as a crucial signal in next-generation security and communication technologies, such as quantum communication, quantum cryptography, and photonic quantum information processing, which is why related optical sensor technologies are attracting significant worldwide attention.
□ Conventional circularly polarized light sensors typically require the light-absorbing material itself to possess a specific helical orientation, known as a “chiral structure.” This approach not only limits the range of usable materials but also confines detection to narrow spectral regions, such as ultraviolet or visible light. Extending this technology into the infrared region, which is essential for quantum communication and optical sensing, has previously posed a major technical challenge.
□ Professor Jiwoong Yang’s team overcame these limitations with an unconventional design: instead of introducing a chiral structure into the light-absorbing material, they incorporated it into the pathway through which electrons travel (the charge transport route). The team developed a zinc oxide (ZnO) electron transport layer combined with chiral substances and applied it to a quantum-dot photodiode, successfully achieving the selective transmission of electrons with a specific spin orientation. When electrons generated by CPL pass through this specialized layer, differences in current arise depending on their spin state, thereby enabling direct detection of the light’s rotational direction.
□ The newly developed quantum-dot optical sensor can detect CPL across an “ultra-wideband” spectral range, encompassing ultraviolet, visible, near-infrared, and short-wave infrared regions. Achieving the ability to capture polarization information over such a broad wavelength range with a single device is considered highly exceptional. Furthermore, the sensor demonstrated a remarkably high performance of 10¹² Jones—a measure of photodetector sensitivity—indicating significant commercial potential.
□ “This research is significant in that it presents a new principle for optical sensors capable of detecting the spin information of photons,” stated Professor Jiwoong Yang. “It is highly likely to serve as a core sensor technology driving diverse fields of quantum optoelectronics, including quantum communication, quantum sensing, next-generation image sensors, and secure optical communication.”
□ This research was supported by the Nano and Materials Technology Development Program of the Ministry of Science and ICT and the National Research Foundation of Korea, as well as the International Joint Technology Development Program of the Ministry of Trade, Industry and Energy and the Korea Institute for Advancement of Technology. The results have been published in Advanced Materials —a leading international journal in the field of materials science.
Advanced Materials
Broadband Circularly Polarized Light Detection via Spin-Selective Charge Transport in Quantum Dot Photodiodes
2-Feb-2026