Electroluminescence emission from polariton states in GaAs-based   semiconductor microcavities
  The authors report the observation of electroluminescence from GaAs-based semiconductor microcavities in the strong coupling regime. At low current densities the emission consists of two peaks, which exhibit anti-crossing behaviour as a function of detection angle and thus originate from polariton states. With increasing carrier injection we observe a progressive transition from strong to weak coupling due to screening of the exciton resonance by free carriers. The demonstration that polariton emission can be excited by electrical injection is encouraging for future development of polariton lasers. 
A. A. Khalifa, A. P. D. Love, D. N. Krizhanovskii, M. S. Skolnick,   J.S.Roberts