Negatively charged quantum well polaritons in a GaAs/AlAs microcavity: An analog of atoms in a cavity

The negatively charged exciton (X-) is observed to strongly couple with the microcavity- (MC-)confined photons in a GaAs quantum well containing a two -dimensional electron gas with 0 < n(e) less than or equal to 3 X 10(10) cm (-2). This strong coupling results in a formation of charged polaritons. Th e coupling strength is found to depend on root n(e), in analogy to two-leve l atoms in a cavity. The analysis of the reflection and photoluminescence s pectra shows that X- is strongly admired with the neutral exciton via their coupling with the MC photons. The linewidth dependence on n(e) indicates t hat electron-polariton scattering is effective.