Development and characterization of intense laser-induced surface-plasma high-harmonic generation

Ultra-intense and ultra-short laser technology provides a unique platform for studying strong-field physics, ultrafast dynamics, and new states of matter in the extreme nonlinear regime. Surface High Harmonic Generation (SHHG) driven by intense laser-plasma interactions offers a reliable route to obtain high-peak-power-density extreme ultraviolet (XUV) to soft X-ray radiation, characterized by high single-pulse energy, attosecond pulse duration, and excellent spatio-temporal coherence. This paper summarizes recent research progress by our team in enhancing the brightness, transmission quality, and diagnostic techniques of SHHG sources. We have constructed a comprehensive experimental platform for high-repetition-rate gas and surface high harmonic generation, systematically conducting SHHG experiments on platforms ranging from kilohertz-repetition-rate to petawatt-peak-power laser systems. By implementing waveform shaping and pre-pulse control techniques, we have verified the tuning pathways and optimization potential of harmonic conversion efficiency and cut-off frequencies across different energy scales. Furthermore, we have developed advanced XUV wavefront diagnostic techniques based on high-numerical-aperture Hartmann Wavefront Sensors (HWS), combined with full temporal characterization schemes , the Spectral Phase Interferometry for Direct Electric Field Reconstruction (SPIDER) and Spatially Encoded Arrangement for SPIDER(SEA-SPIDER), in conjunction with near-to-far-field propagation algorithms, enabling precise quantification and control of the spatio-temporal properties of SHHG sources. Our results verify the influence of driving laser parameters—such as pulse duration, contrast, and carrier-envelope phase (CEP)—on the harmonic emission mechanism and output quality. These findings establish a solid technical and physical foundation for developing highly stable, controllable, tabletop attosecond coherent sources and their applications in precision metrology and material dynamics research.