Pulse Characterization via Two-Photon Auto-Correlation Signals for Multi-Color Pulse Trains in a Systematic Approach*

Recent advancements in ultrashort vacuum and deep ultraviolet pulses have heightened the challenge of precise pulse characterization. To address this, we extend traditional autocorrelation techniques, typically applied to single-color pulse duration measurements, to a broader methodology capable of reconstructing multi-color pulses. Leveraging analytic solutions for two-photon ionization of atoms by Gaussian pulses, we develop an advanced approach that decomposes complex pulses into multiple Gaussian components, each corresponding to distinct frequency combinations [1], [2]. Our method begins with the construction of well-defined, yet unphysical, pulses to isolate and study key characteristics such as pulse width and temporal central peak behavior. We then applied this framework to reconstruct a pulse train from the high harmonic generation spectrum of Helium, integrating insights from our systematic approach to elucidate the influence of varying frequency components on the temporal amplitude and phase dynamics of the electric field. This comprehensive analysis offers new perspectives on the interplay between color components in shaping pulse behavior.

[1] S. Walker, R. Reiff, A. Jaron-Becker, and A. Becker, Opt. Lett. 46, 3083 (2021)

[2] K. Finger, B. Ghomashi and A. Becker, Opt. Express (in press)