  We report the canonical properties of Bose-Einstein condensation of
polaritons, seen previously in many low-temperature experiments, at room
temperature in a GaAs/AlGaAs structure. These effects include a nonlinear
energy shift of the polaritons, showing that they are not non-interacting
photons, and dramatic line narrowing due to coherence, giving coherent emission
with spectral width of 0.24 meV at room temperature with no external
stabilization. This opens up the possibility of room temperature nonlinear
optical devices based on polariton condensation.
