The OSA reported the scientific research achievement produced by a student in Zhuguang class of our college

   Recently, Optics Express, a SCI journal owned by the Optical Society of America (Optica), published a research paper online (title: Tri-channel metasurface for watermarked structural-color nanoprinting and holographic imaging). It should be noted that Naixuan Zhao, an undergraduate in the 2019 Zhuguang class (逐光班), was listed as the first author of the paper. The paper was quickly designated as “Editors' Pick” after publication, and the Optica news concurrently conducted an interview with the Micro-nano Optics research team of our college. The news release was published online as a cover of the Optica website, and was subsequently repeated by some international academic medias such as Phys.org and EurekAlert. 
        In this work, researchers developed a three-channel metasurface capable of producing invisible watermarks and holographic images by merging orientation degeneracy with spectral and phase manipulations of nanostructures. Researchers employed the optical path condition as the key to achieve the switching between channels. Specifically, when the metasurface is exposed to natural light, nanostructures with various geometric parameters immediately alter the spectrum of either transmitted or reflected light, which helps to display a desired structural-color nanoprinting image on the surface of the metasurface (channel 1). When an optical analyzer is introduced to change the polarization direction of the output light, nanostructures with different but non-complementary orientation angles can be used to accomplish polarization-sensitive spectral manipulation, allowing the watermark pattern to cover the original structural-color nanoprinting image (channel 2). When a continuum laser is utilized as the illumination, nanostructures with complementary orientation angles can be used to generate different geometric phase delays, and then a holographic anti-counterfeiting image can be projected in the far-field (channel 3). 
        As shown in the experiment, unwatermarked and watermarked structural-color nanoprinting images possess high polarization sensitivity as well as bright visual effect. Besides, clear holographic images can be observed in a broad wavelength range from 480 nm to 650 nm. In order to realize active optical manipulation and develop more highly-integrated optical meta-devices, researchers intend to combine the metasurface with some interesting materials such as liquid crystal or black phosphorus in their further research. They truly hope to promote the practical application of metasurface in many important fields including high-end anti-counterfeiting, ultracompact display, high-density optical storage, consumer electronics, etc.
 
        After careful study in the Micro-nano Optics Lab, Naixuan Zhao has learned many research skills such as electromagnetic simulating skill, material analyzing skill and metasurface experimental skill. Now she has greatly improved her research ability, and is about to enroll in a direct Ph.D program at the School of Future Technology of Peking University.
 
        Naixuan Zhao’s work was interviewed and selected as the cover of the Optica website.

EurekAlert, a subsidiary of the American Association for the Advancement of Science (AAAS), reported the achievements of Naixuan Zhao.

Related URL:
Optica News report：
https://www.optica.org/en-us/about/newsroom/news_releases/2022/september/metasurface_engineered_to_create_three_different_i/

Phys.org report:
https://phys.org/news/2022-09-metasurface-images-illumination.htm

EurekAlert report：
https://www.eurekalert.org/news-releases/966131