Resonantly enhanced continuous-wave four-wave mixing with spontaneously generated coherence in a five-state cold atomic medium

Using Schr\"odinger-Maxwell formalism, we propose and analyze a continuous-wave four-wave mixing (FWM) scheme for the generation of coherent light in a five-state double-\Lambda atomic system with or without spontaneously generated coherence (SGC) based on electromagnetically induced transparency (EIT). We derive the corresponding explicit analytical expressions for the generated FWM field under the steady-state condition. The influence of hyperfine sublevel and SGC effect on the amplitude of the generated FWM field is predicted in details via the derived analytical expressions. We also give a brief discussion on the experimental realization of the proposed scheme.