Abstract We investigate the amplification mechanism in a four-level system by both the density-matrix and quantum-jump approaches. We show that the asymmetry between three-photon stimulated emission and one-photon absorption process is responsible for the inversionless amplification of the probe field. We also investigate the effects of spontaneously generated coherence (SGC) on the probe gain, and find that due to the SGC, the probe gain can be greatly enhanced and can be modulated by changing the relative phase between the applied fields.
Received: 14 August 2003
Revised: 12 November 2003
Accepted manuscript online:
PACS:
42.50.Gy
(Effects of atomic coherence on propagation, absorption, and Amplification of light; electromagnetically induced transparency and Absorption)
(Quantum fluctuations, quantum noise, and quantum jumps)
Fund: Project supported in part by the National Natural Science Foundation of China (Grant No 10334010).
Cite this article:
Xu Wei-Hua (徐卫华), Wu Jin-Hui (吴金辉), Gao Jin-Yue (高锦岳) Amplification mechanism and effects of spontaneously generated coherence on the probe gain in a four-level system 2004 Chinese Physics 13 692
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