Abstract

The dynamics of the optical properties of water bulk exposed to femtosecond radiation (Ti-sapphire laser, wavelength 800 nm, intensity ${\sim}{10^{13}} {\rm W}/{{\rm cm}^2}$) was studied in the time window of $\approx 1.5\;{\rm ns}$ using a pump–probe technique. Both the refractive index and absorbance were measured by femtosecond interferometric microscopy, which allowed us to gather deconvoluting quantitative data about the induced processes: solvation of excess electrons, geminate recombination, and development of cavitation. We found that the number of electrons produced by a strong, near infrared (NIR) field in the cavitation regime (${ {\lt} 10^{19}}\;{{\rm cm}^{- 3}}$) is much lower than was previously thought. The obtained data clarify the mechanisms of laser energy deposition in water and are of crucial importance to understand intensive light action on aqueous-based systems.

© 2020 Optical Society of America

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