Research progress of dispersion scan techniques in ultrashort pulse characterization

Dispersion scan (D-scan) is an ultrashort laser pulse characterization technique based on dispersion modulation and nonlinear spectral response, and, owing to its extremely simple optical configuration and high sensitivity to broadband spectra and phase evolution, it has developed into an important tool in the field of ultrashort pulse characterization. Focusing on the ability of D-scan to meet the demands of real-time operation and robustness, as well as its extension toward extreme parameters such as single-cycle pulses and the deep-ultraviolet region, this paper systematically reviews the key progress of D-scan technology in terms of retrieval algorithm optimization and experimental scheme expansion. First, the evolution of D-scan retrieval algorithms is summarized. This progression traces the shift from early Nelder–Mead and differential evolution algorithms to the current standard generalized pulse retrieval algorithm, and ultimately to deep-learning-based techniques that enable millisecond-level, real-time reconstruction. Particular emphasis is placed on the improvements in computational speed, algorithmic robustness, and noise immunity achieved across these diverse approaches. Regarding experimental techniques, the paper examines second-harmonic-generation (SHG) D-scans based on second-order nonlinearities. It details the technological transition from conventional scanning methods to real-time, single-shot measurements, and highlights recent progress in applying SHG D-scans to vectorial optical field characterization. Subsequently, to circumvent the physical limitations of second-order nonlinearities—specifically concerning multi-octave spectral overlap and phase matching in the DUV region—this review further explores D-scan techniques leveraging third-order nonlinear effects and their derivatives. It elucidates how these methodologies push the application boundaries of D-scan toward the single-cycle limit and into the DUV regime. Finally, current challenges confronting D-scan technology are outlined, including its reliance on external components and its extension to longer wavelengths and longer pulse durations. The paper concludes with an outlook on the future trajectory of D-scan technology within strong-field physics and attosecond science.