  We study the emission properties of confined polariton states in shallow
zero-dimensional traps under non-resonant excitation. We evidence several
relaxation regimes. For slightly negative photon-exciton detuning, we observe a
nonlinear increase of the emission intensity, characteristic of carrier-carrier
scattering assisted relaxation under strong-coupling regime. This demonstrates
the efficient relaxation towards a confined state of the system. For slightly
positive detuning, we observe the transition from strong to weak coupling
regime and then to single-mode lasing.
