The Inversionless Amplification in a Tripod System of 87Rb Atoms in a Magneto-optical Trap

The probe transmission spectra around the atomic transition 52S1/2, F = 2 ? 52P3/2,F' = 2 of 87Rb are measured in a magneto-optical trap by adding a coupling field around the atomic transition 52S1/2, F = 2 ? 52P3/2,F' = 2. The inversionless amplification is observed in the spectrum over the atomic transition 52S1/2, F = 2 ? 52P3/2,F' = 2. The tripod electromagnetically induced transparency is proposed to account for the amplification feature, in which population distributions among these related atomic levels play an important role.