Polaritons in semiconductor microcavities can experience a Bose-Einstein condensation experimentally detectable in the spectrum of the emitted light. Scattering with noncondensed particles as well as self-interaction in the condensate provoke phase diffusion limiting the coherence of the polariton condensate. We present a theoretical analysis of self-interaction effects on the lineshape of the emission from a polariton laser. Our calculations, for CdTe microcavities, show that there is an optimum pump at which the linewidth of the emitted light is reduced down to $1\mu e\mathrm{V}.$

• Received 9 January 2003

DOI:https://doi.org/10.1103/PhysRevB.67.161310