  The photon blockade is a hallmark of quantum light transport through a single
two-level system that can accomodate only one photon. Here, we theoretically
show that two-photon transmission can be suppressed even for a seemingly
classical system with large number of quantum dots in a cavity when the
biexciton nonlinearity is taken into account. We reveal the nonmonotonous
dependence of the second-order correlation function of the transmitted photons
on the biexciton binding energy. The blockade is realized by proper tuning the
biexciton resonance that controls the collective superradiant modes.
