Gun-Yeal Lee

All Publications

• Full-colour 3D holographic augmented-reality displays with metasurface waveguides. Nature Gopakumar, M., Lee, G. Y., Choi, S., Chao, B., Peng, Y., Kim, J., Wetzstein, G. 2024

  Abstract

  Emerging spatial computing systems seamlessly superimpose digital information on the physical environment observed by a user, enabling transformative experiences across various domains, such as entertainment, education, communication and training1-3. However, the widespread adoption of augmented-reality (AR) displays has been limited due to the bulky projection optics of their light engines and their inability to accurately portray three-dimensional (3D) depth cues for virtual content, among other factors4,5. Here we introduce a holographic AR system that overcomes these challenges using a unique combination of inverse-designed full-colour metasurface gratings, a compact dispersion-compensating waveguide geometry and artificial-intelligence-driven holography algorithms. These elements are co-designed to eliminate the need for bulky collimation optics between the spatial light modulator and the waveguide and to present vibrant, full-colour, 3D AR content in a compact device form factor. To deliver unprecedented visual quality with our prototype, we develop an innovative image formation model that combines a physically accurate waveguide model with learned components that are automatically calibrated using camera feedback. Our unique co-design of a nanophotonic metasurface waveguide and artificial-intelligence-driven holographic algorithms represents a significant advancement in creating visually compelling 3D AR experiences in a compact wearable device.

  View details for DOI 10.1038/s41586-024-07386-0

  View details for PubMedID 38720077

  View details for PubMedCentralID 8208705

• Metasurface eyepiece for augmented reality. Nature communications Lee, G. Y., Hong, J. Y., Hwang, S., Moon, S., Kang, H., Jeon, S., Kim, H., Jeong, J. H., Lee, B. 2018; 9 (1): 4562

  Abstract

  Recently, metasurfaces composed of artificially fabricated subwavelength structures have shown remarkable potential for the manipulation of light with unprecedented functionality. Here, we first demonstrate a metasurface application to realize a compact near-eye display system for augmented reality with a wide field of view. A key component is a see-through metalens with an anisotropic response, a high numerical aperture with a large aperture, and broadband characteristics. By virtue of these high-performance features, the metalens can overcome the existing bottleneck imposed by the narrow field of view and bulkiness of current systems, which hinders their usability and further development. Experimental demonstrations with a nanoimprinted large-area see-through metalens are reported, showing full-color imaging with a wide field of view and feasibility of mass production. This work on novel metasurface applications shows great potential for the development of optical display systems for future consumer electronics and computer vision applications.

  View details for DOI 10.1038/s41467-018-07011-5

  View details for PubMedID 30385830

  View details for PubMedCentralID PMC6212528

• Complete amplitude and phase control of light using broadband holographic metasurfaces. Nanoscale Lee, G. Y., Yoon, G., Lee, S. Y., Yun, H., Cho, J., Lee, K., Kim, H., Rho, J., Lee, B. 2018; 10 (9): 4237-4245

  Abstract

  Reconstruction of light profiles with amplitude and phase information, called holography, is an attractive optical technology with various significant applications such as three-dimensional imaging and optical data storage. Subwavelength spatial control of both amplitude and phase of light is an essential requirement for an ideal hologram. However, traditional holographic devices suffer from their restricted capabilities of incomplete modulation in both amplitude and phase of visible light; this results in sacrifice of optical information and undesirable occurrences of critical noises in holographic images. Herein, we have proposed a novel metasurface that is capable of completely controlling both the amplitude and phase profiles of visible light independently with subwavelength spatial resolution. The full, continuous, and broadband control of both amplitude and phase was achieved using X-shaped meta-atoms based on the expanded concept of the Pancharatnam-Berry phase. The first experimental demonstrations of the complete complex-amplitude holograms with subwavelength definition at visible wavelengths were achieved, and excellent performances with a remarkable signal-to-noise ratio as compared to those of traditional phase-only holograms were obtained. Extraordinary control capability with versatile advantages of our metasurface paves a way to an ideal holography, which is expected to be a significant advancement in the field of optical holography and metasurfaces.

  View details for DOI 10.1039/c7nr07154j

  View details for PubMedID 29350732

• Metasurface folded lens system for ultrathin cameras. Science advances Kim, Y., Choi, T., Lee, G. Y., Kim, C., Bang, J., Jang, J., Jeong, Y., Lee, B. 2024; 10 (44): eadr2319

  Abstract

  Slim cameras are essential in state-of-the-art consumer electronics such as smartphones or augmented/virtual reality devices. However, reducing the camera thickness faces challenges primarily due to the thick lens systems. Current lens systems, composed of stacked refractive lenses, are fundamentally constrained from becoming thinner due to the presence of empty spaces between lenses and the excessive volume of each lens. Here, we present a lens system using metasurface folded optics to overcome these pervasive issues. In our design, metasurfaces are arranged horizontally on a glass wafer and direct light along multifolded paths inside the substrate. This approach achieves an ultra-slim lens system with a thickness of 0.7 millimeters and 2× thinner relative to the EFL, thereby overcoming the inherent limitations of conventional optical platforms. It delivers quasi-diffraction-limited imaging quality with a 10° field of view and an f number of 4 at an operational wavelength of 852 nanometers. Our findings provide a compelling platform for compact cameras using folded nano-optics.

  View details for DOI 10.1126/sciadv.adr2319

  View details for PubMedID 39475595

• Freeform metasurface color router for deep submicron pixel image sensors SCIENCE ADVANCES Kim, C., Hong, J., Jang, J., Lee, G., Kim, Y., Jeong, Y., Lee, B. 2024; 10 (22): eadn9000

  Abstract

  Advances in imaging technologies have led to a high demand for ultracompact, high-resolution image sensors. However, color filter-based image sensors, now miniaturized to deep submicron pixel sizes, face challenges such as low signal-to-noise ratio due to fewer photons per pixel and inherent efficiency limitations from color filter arrays. Here, we demonstrate a freeform metasurface color router that achieves ultracompact pixel sizes while overcoming the efficiency limitations of conventional architectures by splitting and focusing visible light instead of filtering. This development is enabled by a fully differentiable topology optimization framework to maximize the use of the design space while ensuring fabrication feasibility and robustness to fabrication errors. The metasurface can distribute an average of 85% of incident visible light according to the Bayer pattern with a pixel size of 0.6 μm. The device and design methodology enable the compact, high-sensitivity, and high-resolution image sensors for various modern technologies and pave the way for the advanced photonic device design.

  View details for DOI 10.1126/sciadv.adn9000

  View details for Web of Science ID 001235968800002

  View details for PubMedID 38809981

  View details for PubMedCentralID PMC11135393