  Polariton lattice condensates provide a platform for on chip quantum
emulations. Interactions in extended polariton lattices are currently limited
by the intrinsic photonic disorder of microcavities. Here, we fabricate a
strain compensated planar GaAs/AlAs microcavity with embedded InGaAs quantum
wells and report on polariton condensation under non-resonant optical
excitation. Evidence of polariton condensation is supported spectroscopically
both in reflection and transmission geometry, whilst the observation of a
second threshold to photon lasing allows us to conclusively distinguish between
the strong- and weak-coupling non-linear regimes.
