High-harmonic generation in a metasurface

The nonlinear optical effects arising from the interaction between ultrafast lasers and metasurfaces have become a significant focus of photonics research. Among these effects, high-order harmonic generation is regarded as an effective pathway toward realizing extreme ultraviolet light sources and attosecond pulse generation. High-harmonic generation (HHG) based on metasurfaces also offers new strategies for the design of integrated light sources. During this process, the driving conditions for metasurfaces are distinct from those for gas media and bulk materials. Clarifying the physical mechanisms governing the interaction of light with media during HHG, as well as the relationship between these mechanisms and structural parameters, is essential; this understanding also holds great application potential in the research and development of new materials and microscopic dynamics characterization. Here, we review recent advancements in HHG from metasurfaces, focusing on the effects of different resonance modes, structural symmetries, and molecular arrangements in the medium on harmonic yield, polarization control, and the precise manipulation of spatiotemporal distribution. Finally, we discuss improvement strategies for metasurfaces with the aim of more effectively mitigating damping in nonlinear processes, and explore future applications of metasurface-based HHG in frontier fields.