Fluorescent spectra in a four-level atom interacting with strong electromagnetic fields

Abstract

The fluorescent spectrum of a four-level atomic system is studied when one, two or three nearly resonant waves of arbitrary intensities irradiate the system. Calculations are performed with the dressed-atom approach. The spectrum, according the particular case considered, consists of 3, 9, or 13 lines. Simple analytical expressions are given for the frequencies and the probabilities of different transitions.