Bipolariton laser emission from a GaAs microcavity
  Biexciton emission properties were studied in a single GaAs quantum well semiconductor planar microcavity by photoluminescence measurements at low temperatures. At high pump intensity a bipolariton emission appears close to the lower polariton mode. This new mode appears when we detune the cavity resonance out of the lower polariton branch, showing a laser like behavior. Very small lines widths were measured, lying below 110 &#956;eV and 150 &#956;eV for polariton and bipolariton emission respectively. The input/output power (I/O) measurements show that the bipolariton emission has a weaker coupling efficiency compared to previous results for polariton emission. Simultaneous photoluminescence and near field measurements show that the polariton and bipolariton emission are spectrally and spatially separated. 
L. M. Moreira, J. C. Gonzalez, A. G. Oliveira and F. M. Matinaga