Co-existing of dressed non-linear gain and electromagnetically induced absorption

• We use a strong pumping field to generate entangled photon pairs of spontaneous parametric FWM.
• The non-linear gain and electromagnetically induced absorption are observed.
• The parametric amplified FWM is drastically improved by scanning pumping field.

The dressed parametric four-wave mixing (FWM) process has been investigated in hot atomic rubidium vapor. We use a strong pumping field to generate entangled photon pairs of spontaneous parametric FWM (SP-FWM) which can be enhanced by an external dressing effect. Seeding probe beam into the Stokes or anti-Stokes (SP-FWM) channel will form the parametric amplified FWM (PA-FWM) process, then the non-linear gain and electromagnetically induced absorption (EIA) are observed, caused by the internal dressing effect. However, with scanning of pumping field the absorbing background will vanish, which will result in drastic increase in PA-FWM signal gain.