Power broadening revisited: theory and experiment

摘要

The spectral width of an atomic absorption line, observed with a steady light source, typically increases as the light intensity increases, an effect known as power broadening. In this paper, we point out classes of pulsed-light observations where power broadening does not always occur. We present analytical and numerical results, supported by experimental data of coherent pulsed excitation probed by photoionization, which show that the extent of power broadening depends crucially upon the nature of excitation and the type of measurement. In particular, we show that a spectral line obtained from measurement performed after pulsed excitation exhibits no power broadening. For pulsed excitation and continuous measurement, the spectral line contains two components: a power-broadened signal collected during the excitation and an unbroadened signal collected after the excitation.