title: Observation of the fluorescence spectrum for a driven cascade model system in atomic beam.
abstract: We experimentally study the resonance fluorescence from an excited two-level atom when the atomic upper level is coupled by a nonresonant field to a higher-lying state in a rubidium atomic beam. The heights, widths and positions of the fluorescence peaks can be controlled by modifying the detuning of the auxiliary field. We explain the observed spectrum with the transition properties of the dressed states generated by the coupling of the two laser fields. We also attribute the line narrowing to the effects of Spontaneously Generated Coherence between the close-lying levels in the dressed state picture generated by the auxiliary field. And the corresponding spectrum can be viewed as the evidence of Spontaneously Generated Coherence. The experimental results agree well with calculations based on the density-matrix equations.
authors.affiliation: State Key laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin 130033, China.
authors.forename: Si-Cong
authors.initials: SC
authors.lastname: Tian
authors.forename: Chun-Liang
authors.initials: CL
authors.lastname: Wang
authors.forename: Cun-Zhu
authors.initials: CZ
authors.lastname: Tong
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Wang
authors.forename: Hai-Hua
authors.initials: HH
authors.lastname: Wang
authors.forename: Xiu-Bin
authors.initials: XB
authors.lastname: Yang
authors.forename: Zhi-Hui
authors.initials: ZH
authors.lastname: Kang
authors.forename: Jin-Yue
authors.initials: JY
authors.lastname: Gao
mesh_terms: D003198:Computer Simulation; D005453:Fluorescence; D008027:Light; D008962:Models, Theoretical; D011789:Quantum Theory; D012542:Scattering, Radiation