Ultrafast dynamic evolution of multilevel systems in medium-strength laser fields

TL;DR

This paper investigates the ultrafast evolution of multilevel atomic systems under medium-strength laser fields using transient absorption measurements and an analytical perturbation theory model, revealing insights into laser-matter interactions.

Contribution

It introduces a modified perturbation theory model to explain spectral features and quantifies system dynamics through amplitude and phase modulation factors.

Findings

Spectral features explained by the analytical model.

Quantitative analysis of system evolution in different scenarios.

Insights into the transition between weak and strong field regimes.

Abstract

The ultrafast dynamic evolution of an atomic system under medium-strength laser fields is studied by performing transient absorption measurement. An analytical model developed from perturbation theory with a modified transition dipole moment is presented to explain the spectral features of the multilevel system. By fitting the measured absorption spectra to the model, the system's dynamic evolution is quantified by different amplitude and phase modulation factors in the pump--probe and probe--pump scenarios. This study provides a way to understand laser--matter interaction in the transition area between the strong-field and weak-field regimes.