Junsuk Rho

Junsuk Rho

韩国浦项科技大学，教授

Pohang University of Science and Technology, Professor

Prof. Rho is a Yeon-San (延山) Endowed Chair Professor and Mu-Eun-Jae (无垠斋) Endowed Chair Professor at Pohang University of Science and Technology (POSTECH), Korea, with a joint appointment in the Department of Chemical Engineering, Mechanical Engineering, and Electrical Engineering. He received his Ph.D. at the University of California, Berkeley (2013), M.S. at the University of Illinois, Urbana-Champaign (2008) and B.S. at Seoul National University, Korea (2007) all in Mechanical Engineering. Prior joining POSTECH, he conducted postdoctoral research in Materials Sciences Division & Molecular Foundry at Lawrence Berkeley National Laboratory, and also worked as a principal investigator (Ugo Fano Fellow) in Nanoscience and Technology Division & the Center for Nanoscale Materials at Argonne National Laboratory. Prof. Rho has authored and co-authored more than 450 high-impact journal papers including Science and Nature. He is also the recipients of several notable honors and awards such as US Department of Energy Argonne Named fellowship (2014), Korean Presidential Early Career Award for Scientists and Engineers (2019), Member of the Young Korean Academy of Science and Technology (Y-KAST) (2020), Associate Member of the National Academy of Engineering of Korea (NAEK) (2022), Fulbright Visiting Scholar Fellowship (2022), Northwestern Simpson Fellowship (2022), Clarivate Highly Cited Researcher (2023, 2024), Elsevier/Stanford World Top 2% Scientist (2021-2025), ACS Nano Lectureship (2024). He serves 13 editorial positions including Light: Science and Applications (Springer-Nature), Microsystems and Nanoengineering (Springer-Nature), npj Nanophotonics (Springe-Nature).

用于成像、传感和显示的光学超表面

摘要：

超构材料与超构表面是由纳米结构阵列组成的新型光学元件。它们具有超紧凑的结构优势，能够对亚微米级物体进行成像，分辨率接近光的衍射极限。其成像应用范围从简易显微镜到更先进的光学成像领域，如三维传感器、激光雷达、生物成像及摄像头。成像波长范围也日趋多样化，以支持各类成像需求。

工作在紫外波段的超构透镜，由于光波长短，可实现高分辨率成像。在可见光波段，超构透镜可用于虚拟现实（VR）/增强现实（AR）显示成像。近红外超构透镜在夜视设备和内窥镜中具有应用潜力。成像波长进一步扩展至超声波段，可用于光声显微成像。此外，弹性超构透镜可应用于能量收集，声学超构透镜则可用于聚焦声波。

超构透镜还能实现多功能成像：可调节焦距、基于自旋实现三通道成像，甚至能对单光子源发出的光子进行成像。尽管超构透镜可在多波段工作，并为众多成像应用提供多样化功能，但其设计目前尚不具备可扩展性，大面积设计计算量大且成本高昂。为此，研究者开发了严格耦合波分析（RCWA）及基于人工智能与数据库的高效计算方法。

然而，即使大面积设计能力有所突破，其商业化进程仍受制于高成本、低产能等制造瓶颈。为降低超构透镜的生产成本，纳米压印光刻技术已被采用。为解决传统压印树脂折射率低的问题，研究者通过掺入高折射率颗粒，开发出了一步压印成型平台。另一方面，深紫外光刻技术已被用于提升产能，实现晶圆级大面积超构表面制造。但由于该方法制造成本过高，当前研究聚焦于先通过光刻技术制备超构表面母版，再利用晶圆级纳米压印技术进行批量复制。这些可扩展的制造方法有望推动超构透镜超越研究阶段，真正走向实际应用。

Optical Metasurfaces for Imaging, Sensing, and Display

Abstract：

Metamaterials and metasurfaces are novel optical components composed of nanostructure arrays. They offer the advantage of an ultracompact form factor and can image submicron objects with resolution approaching the diffraction limit of light. The scope of this imaging extends from simple microscopes to more advanced light imaging applications such as 3D sensors, LiDAR, bio-imaging, and cameras. The wavelength range of imaging is also diversifying to support various imaging applications. Metalenses operating in the UV region enable high-resolution imaging due to the short wavelength of light. In the visible light spectrum, metalenses can be used for imaging in VR/AR displays. Near-infrared metalenses have potential applications in night vision devices and endoscopes. The wavelength range extends further to include the ultrasound region, where it can be used in photoacoustic microscopy. Additionally, elastic metalenses can be applied for energy harvesting, and acoustic metalenses can be used to focus sound waves. Furthermore, metalenses can perform imaging with various functionalities. They can tune their focal length, demonstrate trichannel imaging based on spin, and even image single photons emitted from a source. While metalenses operate across various wavelengths and offer diverse functionalities for numerous imaging applications, their design is currently not scalable, making large-area designs computationally heavy and expensive. To address this, efficient computational methods like RCWA and AI/DB-based design approaches have been developed. However, even with advances in large-area design capabilities, their commercialization has been hindered by manufacturing limitations such as high cost and low throughput. To reduce the production cost of metalenses, nanoimprint lithography has been employed. To address the low refractive index of conventional imprint resins, high-refractive-index particles are incorporated, creating a one-step printable platform On the other hand, ArF photolithography has been used to overcome low throughput and produce large-area metasurfaces at wafer scale. However, due to the high manufacturing costs associated with this method, research has been conducted on mass-producing metasurfaces by using wafer-scale nanoimprint technology to replicate metasurfaces initially created through photolithography. These scalable manufacturing approaches are expected to propel metalenses beyond the research level and into practical applications.