Xin Li

The pursuit of high‐dimensional optical information, particularly spectrum and polarization, has been a persistent goal in both scientific research and engineering applications. However, conventional spectro‐polarimetric imaging systems are typically constrained by bulky hardware, complex optical configurations, and heavy computational burdens, which severely limit their deployment on miniaturized platforms. In this study, we propose a lightweight spectro‐polarimetric imaging method enabled by a height‐varying metasurface via two‐photon polymerization lithography, where out‐of‐plane height modulation and in‐plane geometric shapes are jointly exploited to achieve a broader spectral modulation range and different polarimetric responses. By combining the designed metasurface with a newly built reconstruction algorithm, spectro‐polarimetric images are successfully reconstructed from a single grayscale image, with an average polarization angle error of 3.02° for uniform objects and an average PSNR of 35.86 dB, SSIM of 0.93, and spectrum fidelity of 98.45% for a complex object, demonstrating the high reconstruction quality of the proposed method. This work provides a compact and efficient route toward snapshot acquisition of high‐dimensional light information, offering strong potential for integration into miniaturized imaging platforms.

Ultrafast continuous imaging techniques face inherent trade-offs among sequence depth, temporal resolution, and system complexity. To address this, we developed Supercontinuum Photon Encoded Extreme Dynamic Snapshot Imaging (SPEED-SI). This technique employs precise spectral segmentation at the Fourier plane, discretizing a supercontinuum pulse into multiple independent spectral channels. Our system enables single-shot ultrafast imaging at 36 frames per acquisition with femtosecond exposure time and a peak frame rate of 10.5 trillion frames per second (Tfps). By implementing a higher-density diffraction grating, we further expanded the sequence depth to 45 frames and achieved an enhanced peak frame rate of 17.9 Tfps, which represents the highest sequence depth reported for direct continuous imaging on the femtosecond timescale. The system outputs high-fidelity images in real time without computational reconstruction or associated artifacts. Moreover, ultraviolet-continuum generation from a calcium fluoride crystal demonstrates the potential for further expansion of the spectral bandwidth and sequence depth, establishing SPEED-SI as a powerful tool for investigating ultrafast phenomena.

Optical metasurfaces to perform optical analog spatial differentiation operations and image edge detection processing is a currently hot topic. However, some metasurface differentiators are limited by polarization dependence, narrow operating bandwidth, low numerical aperture (NA), requiring for additional polarization elements or digital processing, and under coherent light illumination conditions. Here, we use the optical angular dispersion effect based on resonant dielectric metasurface, to realize the Laplacian differential operation in the real space directly, which can address these critical metrics for p- and s-polarized light. Moreover, the broadband operating range of the metasurface differentiator can be obtained by exciting and detuning the electric toroidal dipole (ETD) and magnetic toroidal dipole (MTD) resonances. We experimentally demonstrate that azimuthal-insensitive Laplace differential operations and dual-polarization second-order two-dimensional edge detection with NA up to 0.64 and spectral bandwidths of nearly 100 nm from 750 to 850 nm. In addition, broadband incoherent and unpolarized edge detection experiments are also carried out with satisfactory performance. Our work will pave the way for free-space realization of high-efficiency, broadband parallel optical-computation and image-processing in machine-vision, biomedical, and optical microscopy.

Metalenses tremendously manipulate the incident light to focus beam by carefully selecting and arranging the meta-atoms. However, their integration with optical components is a challenge. Existing approaches often involve bulky intermediary optics or limited alignment precision, restricting their practical applications in fiber-based systems. In this study, we propose and implement a method for integrating a dual-channel metalens with a spun fiber, enabling focusing at 210 µm and 130 µm under two circularly polarized channels with opposite handedness. This method utilizes an align-bond-peel process to rapidly and conveniently integrate metalens on the fiber tip while ensuring excellent performance. It holds immense potential for many applications such as polarization-multiplexed optical communication, fiber-integrated sensing, and advanced photonic systems, where compact, efficient, and multifunctional optical devices are increasingly in demand.

Metasurfaces are ultra‐thin micro‐nano elements, have abundant freedoms, and are widely used in light field transformation. The Jones matrix of single‐layer birefringent metasurfaces have at most 6 degrees of freedom, which limits the richness and diversity of light field transformation. Bilayer metasurfaces have more design channels and functionality than single‐layer metasurfaces. By mathematical derivation, the decomposition method of the bilayer metasurface unitary Jones matrix is provided. Further, inspired by double‐phase holography, arbitrary complex Jones matrix is decomposed and realized by bilayer metasurface and achieves analytical decoupling of all 4 complex components of the Jones matrix. As the theoretical verification, spin‐orbit angular momentum mapping and four‐channel complex holography are realized by the bilayer metasurface. The decomposition method is completely analytical, universal, and easy to implement. It is of great significance for the transformation of light field, information transmission, and optical encryption based on metasurfaces.

As an important method of image processing, image differentiation enables edge detection of targets to achieve recognition of object features and information compression and the computation speed can be boosted by optical information techniques. Traditional optical image differentiation methods mainly rely on spatial spectrum filtering by using classical 4f system, while some work focus on 1D or single‐direction differentiation. It is only in recent years that the rapid development of metasurfaces has facilitated image differentiation methods. In this work, a Laplace operation device is demonstrated based on a silicon hollow brick dielectric resonant metasurface for incident light field. The optical transfer function (OTF) required by the optical Laplace operation can be obtained by exciting an angularly selective toroidal dipole (TD) resonance supported by the metasurface. This hollow silicon brick differentiator not only realizes 2D second‐order edge detection but also has a numerical aperture close to 0.4 and a broad working wavelength range >100 nm and can be directly integrated with imaging systems. Such metadevice may be potentially applied in the fields of optical sensing, microscopy, machine vision, biomedical imaging, etc.

Three-dimensional (3D) imaging is a crucial information acquisition technology for light detection, autonomous vehicles, gesture recognition, machine vision, and other applications. Metasurface, as a subwavelength scale two-dimensional array, offers flexible control of optical wavefront owing to abundant design freedom. Metasurfaces are promising for use as optical devices because they have large field of view and powerful functionality. In this study, we propose a flat optical device based on a single-layer metasurface to project a coded point cloud in the Fourier space and explore a sophisticated matching algorithm to achieve 3D reconstruction, offering a complete technical roadmap for single-shot detection. We experimentally demonstrate that the depth accuracy of our system is smaller than 0.24 mm at a measurement distance of 300 mm, indicating the feasibility of the submillimetre measurement platform. Our method can pave the way for practical applications such as surface shape detection, gesture recognition, and personal authentication.

In mathematics, general functions can be decomposed into a linear combination of basis functions. This principle can be used for creating an infinite number of distinct geometric patterns based on a finite number of basis patterns. Here, we propose a Dammann vortex metasurface (DVM) for optically generating an array of diverse, diffraction-multiplexed vortex patterns, based on three custom-defined basis patterns. The proposed DVM, with its capability of quantitatively correlating phase and intensity distribution in different diffraction orders, opens up doors for various applications including orbital angular momentum encryptions and quantum entanglement.