Experimental realization of a polariton beam amplifier
  In this report we demonstrate a novel concept for a planar cavity polariton beam amplifier using non-resonant excitation. In contrast to resonant excitation schemes, background carriers are injected which form excitons, providing both gain and a repulsive potential for a polariton condensate. Using an attractive potential environment induced by a locally elongated cavity layer, the repulsive potential of the injected background carriers is compensated and a significant amplification of polariton beams is achieved without beam distortion. 
Dominik Niemietz, Johannes Schmutzler, Przemyslaw Lewandowski, Karol   Winkler, Marc A{\ss}mann, Stefan Schumacher, Sebastia...
cond-mat.mes-hall cond-mat.quant-gas