Observation of multi-Raman gain resonances in rubidium vapor**Project supported by the National Natural Science Foundation of China (Grant Nos. 11374238, 11574247, and 11534008) and the Fundamental Research Funds for the Central Universities, China (Grant No. xjj2014097).

Abstract

We present an experimental study of multi-Raman gain resonances in a hot rubidium vapor. The experiment is performed based on a high-efficiency four-wave mixing process due to the Raman-driven coherence in a double-Λ configuration. The Raman gain resonance for 85Rb atoms under a bias magnetic field is shown to be split into five or six peaks, depending on the orientation of the magnetic field. The formed multi-Raman gain resonances have potential applications in measurement of magnetic fields and generation of multi-frequency correlated twin beams.