Efficient Raman sideband generation in a coherent atomic medium - art. no.013802

We demonstrate the efficient generation of Raman sidebands in a medium cohe rently prepared in a dark state by continuous-wave low-intensity laser radi ation. Our experiment is performed in sodium vapor excited in Lambda config uration on the D-1 line by two laser fields of resonant frequencies omega ( 1) and omega (2), and probed by a third field omega (3). First-order sideba nds for frequencies omega (1), omega (2) and up to the third-order sideband s for frequency omega (3) are observed. The generation starts at a power as low as 10 muW for each input field. Dependences of the intensities of both input and generated waves on the frequency difference (omega (1) - omega ( 2)), on the frequency omega (3), and on the optical density an investigated .