Independent Electrical Control of Phase and Intensity in Second Harmonic Nanophotonic Devices
Unlocking Next-Generation Quantum Communication and Information Processing
Published in Science Advances
A nanophotonic device capable of independently controlling both the intensity and phase of light has been developed.
By applying voltage to this device, researchers can freely modulate the phase and intensity of the second harmonic light, which is light whose frequency has been doubled. This technology is drawing attention as a foundational advancement for next-generation quantum communication and quantum information processing.
On August 25, Professor Lee Jongwon's team from the Department of Electrical and Electronic Engineering at UNIST announced that they have developed an electrically driven nanophotonic device capable of completely independent control over the phase and intensity of frequency-doubled light.
The nanophotonic device developed by the research team is a type of nonlinear optical modulation device. Nonlinear optics refers to phenomena where the frequency and other properties of light change depending on the input intensity as it passes through a special medium. In quantum technology, quantum entangled light sources must also be generated through such nonlinear conversion processes.
This nanophotonic device is about one ten-thousandth the size of a fingernail, enabling the creation of smaller and lighter devices by replacing bulky traditional media. Unlike existing nanophotonic devices, which could only be operated passively and were therefore difficult to use in practical applications, this device can be activated by applying voltage. It is also possible to independently control both phase and intensity, allowing for the combination of these two pieces of information to encode even more data.
In actual experiments, the intensity of the second harmonic was controlled with a modulation depth close to 100%, and the phase could be freely adjusted over a range from 0 to 360 degrees. Additionally, the magnitude of the nonlinear response was tunable within a range of approximately 0 to 30 nm/V. The research team explained that this means the nonlinear response can reach all combinations on a polar coordinate plane, enabling complete electrical control in the complex phase-intensity space.
The team also succeeded in using this technology to implement phase gratings and amplitude gratings, and to control the diffraction patterns of output signals. These results demonstrate potential for a wide range of applications, including real-time optical wavefront control, high-speed information encoding, and contactless switching.
This technological breakthrough was made possible by the surface structure design of the photonic device. On the device's surface, a nanostructure combining multiple quantum wells and metallic nanocavities is arranged so that two structures with opposite phases (differing by 180 degrees) form a pair.
Professor Lee Jongwon said, "We have presented the world’s first ultra-compact nonlinear optical platform that overcomes the physical limitations of conventional nonlinear optical devices and enables perfect, high-speed, and precise optical wavefront control through electrical manipulation alone. This technology could be expanded as a foundational technology for active quantum optical systems, such as quantum entangled light sources and quantum interference control."
The results of this research were published in Science Advances on July 25, 2025. The study was supported by the Institute for Information & Communications Technology Planning & Evaluation and the National Research Foundation of Korea.
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