Raman scattering in a four-level atomic system with hyperfine structure
Li Jia-Hua (李家华)a, Yang Wen-Xing (杨文星)a, Peng Ju-Cun (彭菊村)b
a Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, China; b Department of Physics, Xiaogan Normal University, Xiaogan 432100, China
Abstract We propose and analyse an efficient Raman scheme for suppressing the absorption of a weak probe beam in a typical four-level atomic system with a nearly hyperfine doublet structure of two higher-lying excited levels for the two cases of transient regime and steady-state process. For the transient process, using the numerical calculations by a nice MATHEMATICA code, we find that the magnitude of the probe absorption at line centre of the probe transition is small compared to the standard three-level atomic system based on electromagnetically induced transparency (EIT). In particular, our results show that the probe absorption can be completely eliminated under the condition of Raman resonance, i.e. we only require that two-photon detuning is zero within the range of the hyperfine two-level frequency gap for the case of the steady state. In contrast to the standard three-level EIT scheme, one of the key advantages of our four-level Raman scheme is that under the Raman resonance condition we can observe one transparency window without the need of exact vanishing of one- and two-photon detuning. As a consequence, the atomic hyperfine structure cannot be a hindrance for obtaining EIT.
Received: 02 December 2003
Revised: 18 November 2004
Accepted manuscript online:
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos 60478029 and 10125419)
Cite this article:
Li Jia-Hua (李家华), Yang Wen-Xing (杨文星), Peng Ju-Cun (彭菊村) Raman scattering in a four-level atomic system with hyperfine structure 2005 Chinese Physics 14 758
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