At low fluences, we observe that PL1 dominates the radiative pumping of the lower polariton, as evidenced by the higher emission intensity at larger in-plane wavevectors. In contrast, when the excitation fluence is increased, the maximum PL intensity shifts towards lower polariton states with smaller �𝑘𝑘 ∥ ���⃗ �, indicating that their population grows with fluence. This suggests that the efficiency with which the incoherent PL2 emission populates the lower polariton branch through radiative pumping increases with fluence.