Metamaterials are artificial materials which can have electromagnetic response characteristics that ordinary materials in nature do not have by selecting different constituent materials and geometric parameters of structural units in metamaterials. However, the development of metamaterials is very limited due to the difficulty of three-dimensional processing processes. Metasurfaces are the two-dimensional counterparts of metamaterials. Compared with metamaterials, metasurfaces have the advantages of simple preparation process, high integration and powerful functions, and have broad application prospects in the fields of classical optics and quantum optics. In the field of classical optics, metasurfaces are mainly used to develop optical components with higher integration and more innovative functions, which is of great significance for the research of integrated optical devices. In the field of quantum optics, metasurfaces can not only reduce the complexity of quantum optics experimental devices, improve their stability and scalability, but also provide a new research platform for quantum optics research. Therefore, exploring the application value of metasurfaces in degrees of freedom such as wavelength, polarization, and orbital angular momentum is crucial to the fields of classical optics and quantum optics.

Field-of-view (FOV) is a critical performance metric for optics and optical systems. Wide FOV optics are widely used in machine vision, augmented/virtual reality (AR/VR), automotive sensing, robotic sensing, biomedical imaging, security surveillance, and more. Conventional wide FOV optics, exemplified by the so-called 'fisheye lenses', involve cascading multiple refractive optical elements to mitigate off-axis aberrations. As a result, for a long time wide-FOV optics have been synonymous with bulky and complicated multi-lens assembly. The compound optics configuration increases the size, weight, cost, and complexity of these optics, severely curtailing their practical deployment.

How to achieve more efficient laser processing in order to meet diverse needs is a vital research topic in the field of ultrafast laser processing. In the past, people used to directly control a single beam laser parameter such as the energy, pulse number and pulse width to achieve the basic requirements. Spatiotemporal characteristics of the incident pulse can be regulated to achieve more precise functional micro/nano-structures by controlling the nonlinear ionization process at the laser focus, which may realize the rapid removal of materials. Ultrafast laser double-fs-pulse sequence has been developed as an effective processing method and is widely used for the processing of material surface and interior, where the ionization process of the material can be dynamically controlled by adjusting the delay time, energy ratio, and polarization state between two sub-pulses.

Quantum entanglement is a key fundamental concept and an enabling feature for various quantum technologies, as recognized in particular by the Nobel Prize in Physics in 2022. When we say two particles are entangled, it means that certain properties of them remain linked, even when they are far apart, a phenomenon that Einstein thought implausible, dubbing it "spooky action at a distance." The photons, quasi-particles of light, can possess entanglement in different degrees of freedom such as frequency, spatial position, and propagation direction. Photon pairs that are entangled in the spatial degrees of freedom represent an essential resource for a broad range of quantum applications, including imaging, communications, and computations. Therefore, photon sources with tunable spatial entanglement are pivotal in quantum photonic technologies. The most common way to generate spatially entangled photon pairs is based on a process called spontaneous parametric down-conversion (SPDC), where a pump photon goes through a quadratically nonlinear material and spontaneously splits into two lower-energy photons that are emitted in different directions. Conventional SPDC sources rely on nonlinear crystals, which are bulky, with a typical thickness on the scale of millimeters to centimeters. In such thick crystals, the emission directions are limited to a certain predefined angle range, making it challenging to flexibly tune the spatial pattern and entanglement of the photon pairs while maintaining the generation efficiency.