Advanced Metasurface Imaging and Display Based on Multidimensional Light Field Manipulation (Invited)

Significance The advent of metasurface technology has marked a revolutionary change in the field of optical engineering. This groundbreaking innovation has opened new doors for manipulating light with an unprecedented level of precision. Metasurfaces, comprised of subwavelength nanostructures, precisely offer control over the phase, amplitude, and polarization of light, enabling the creation of compact, efficient, and highly functional optical components. They show a significant advancement over traditional bulky optical components and have significant implications for various applications, including high-resolution imaging, advanced display technologies, and virtual/ augmented reality systems. In this paper, we reviewed the fundamental principles and recent advances in metasurface platforms for imaging and display applications. Progress The advancement in metasurface research has been significant, transitioning from foundational studies in light control to applied innovations. In this paper, we established a solid foundation for the imaging mechanism of metasurfaces, starting from a generalized Snell's Law to the phase formulas for focusing light at arbitrary angles to a specified location. We thoroughly discussed the principles and applications of achromatic and chromatic imaging based on metasurfaces and delved into the multiplexing functionality of metasurfaces, significantly enhancing their information capacity and functional diversity. The principles and applications of edge imaging based on optical differentiation were also introduced. Starting from the full optical function and combining approaches like metalens array, we analyzed the simultaneous acquisition and computation of multiple optical dimension information. Metasurfaces are unlocking new possibilities for future imaging technologies by controlling light propagation and interaction across different dimensions like time, space, and spectrum. This not only increases the informational content of images but also provides customized imaging solutions for specific applications. As an emerging optical technology, metasurfaces demonstrate substantial potential and necessity in the field of display due to their precise light field manipulation capabilities. They not only achieve optical effects unattainable for traditional technologies but also significantly enhance the energy efficiency and integration of display devices. Holographic display technology based on metasurfaces offers increased controllable degrees of freedom and the capability for three-dimensional displays, greatly expanding the scope of display technology applications and providing new avenues for highly realistic visual experiences. Augmented reality (AR) and virtual reality ( VR) near-eye technologies are playing an increasingly important role in today's world. However, there are still problems of huge volume and low resolution. Metasurface makes it possible to realize thinner and more efficient near- eye display devices, which promotes the further development of AR and VR technologies. Here, we introduced the holographic display based on metasurface, including scalar holography and vector holography, and discussed the three-dimensional display technology, including three-dimensional holography and light field display. We also talked about the advancements in AR/ VR technologies enabled by metasurfaces, such as fullcolor displays and waveguide- coupled displays, which promote the further development of AR and VR technologies. In this study, we explored and compared the design parameters for metasurfaces in imaging and display capabilities, analyzed the numerous challenges faced in the application of metasurface imaging and display, and proposed viable solutions to these challenges. It is believed that with the advancement of technology and innovation in principles, imaging and display technologies will further develop. In addition, we innovatively introduced metasurface imaging and display devices through reverse optimization algorithms. Unlike traditional forward design that consumes extensive computational time and resources, this method enables faster and more efficient dataset searches, yielding superior results. The inverse design process typically includes gradient-based methods (like topology optimization, adjoint methods, or level set methods), evolutionary methods (such as genetic algorithms or particle swarm optimization), and machine learning (neural networks). We presented various intelligent computational approaches and analyzed their advantages and disadvantages. From an interdisciplinary perspective, metasurfaces have innovatively addressed complex scientific and engineering challenges, finding extensive research applications in computational imaging, super- resolution microscopy, optical micromanipulation, dynamic tunable displays, and non-classical quantum realms. By integrating with computational imaging, metasurfaces enable the processing and extraction of high-dimensional image information. Combined with biomedicine, they give full play to the advantages of metasurface volume to realize microscopic and biological endoscopy imaging of cells and have unique advantages in optical micromanipulation technology. A variety of materials and optical technologies can be combined to achieve dynamically adjustable optical responses for different scenarios. Non-classical imaging and display can also be realized in the quantum field. By taking advantage of the great advantages of metasurfaces combined with collaborative innovation in multiple fields to overcome existing technical barriers, it provides a forwardlooking perspective on the development direction of this dynamic field, thus driving leaps forward in the entire optical imaging and display technology. Conclusions and Prospects The extensive application prospects of metasurface technology in various fields highlight its transformative potential and exciting future directions. Further studies are required to address the challenges in large- scale fabrication, integration, commercialization, and applications of metasurfaces. We envisage metasurfaces will enable the next generation of flat optical components and systems with superior imaging resolution, efficiency, functionality, and compactness. The combination of metasurface and other advanced technologies is expected to open up new horizons for photonics.