Controlled Light Wavelengths Electrically... UNIST Develops World's First 'Nonlinear Optical Metasurface'

Record-Breaking Peak in Light Conversion Efficiency, New Horizons in Light Wavelength Modulation

Professor Jongwon Lee's team (front row, far right) from the Department of Electrical and Electronics Engineering at UNIST has developed the world's first 'nonlinear optical metasurface.'

[Asia Economy Yeongnam Reporting Headquarters, Trainee Reporter Lee Seryeong] A domestic research team has developed the world’s first ‘nonlinear optical metasurface’ that changes the wavelength of light using electricity.

The research team led by Professor Lee Jongwon of the Department of Electrical and Electronic Engineering at Ulsan National Institute of Science and Technology (UNIST) published these research results on the 23rd local time in Nature Photonics, the most prestigious journal in the field of optics.

The research was supported by the Korea Research Foundation’s Mid-career Researcher Support Project, Nano and Materials Technology Development Project, and Basic Research Laboratory Project.

Nonlinear optics is an optical modulation technology that changes the frequency of light through strong interactions between light and matter, modulating the wavelength of light by passing it through a thick medium.

It is commonly used in everyday life, such as in green laser pointers, where green lasers are made by modulating the wavelength of relatively easy-to-make infrared light passing through a thick nonlinear medium.

The nonlinear optical metasurface is an artificial material that can reduce the volume of the medium to the thickness of a hair, enabling miniaturization of devices.

Since light only needs to meet the metasurface without considering complex optical alignment, it is expected to enable the creation of paper-thin and lightweight cameras and laser devices.

Professor Lee’s team introduced for the first time a voltage-controlled nonlinear metasurface, moving beyond the previously passive methods that could not be electrically controlled.

The structure consists of a unit cell with a V-shaped metallic plasmonic resonance structure on top of a multiple quantum well semiconductor layer, arranged on a substrate with multiple unit cells smaller than the wavelength of light.

It can independently control not only the wavelength but also the intensity and phase of light, making it applicable to optical modulation encryption technology, holograms, next-generation terahertz wave communication light sources, and quantum information communication light sources.

The team uniquely designed the multiple quantum well (MQW) structure to achieve high optical conversion efficiency even with a thin metasurface.

They improved the world’s best efficiency record they previously held by more than three times, achieving an optical conversion efficiency of 0.24%, setting a new record.

Professor Lee Jongwon stated, “This is the first case of electrically controlling the intensity and phase of nonlinear harmonics generated by a metasurface, opening a new horizon in nonlinear planar optical device technology.”

He also said, “It will be utilized in nonlinear light sources, dynamic nonlinear holograms, nonlinear optical information processing devices, and novel quantum photonic devices.”

Researcher Yoo Jaeyeon said, “By changing the multiple quantum well structure or the plasmonic structure respectively, various functional nonlinear optical devices can be developed in the future.”

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