Lifetime of nonequilibrium carriers in semiconductors from the standpoint of a collective interaction in the process of radiative recombination

InGaAsP/InP laser heterostructures in the continuous pumping regime were investigated by autocorrelation methods. It was shown that below and above the lasing threshold the laser radiation consists of ultrashort coherent pulses and the temporal coherence of these pulses was measured. The dependence of the pulse duration on the pump current was also investigated. The results obtained can be interpreted in terms of collective resonances in the process of radiative recombination. To explain the observed effects the carrier lifetime was treated as a combination of the accumulation time and the collective emission time.