Characterization of two-threshold behavior of the emission from a GaAs microcavity

We compare two regimes indicative of polariton lasing and photon lasing of a planar GaAs/GaAlAs microcavity with zero detuning between the bare cavity mode and the quantum-well exciton. In particular, we investigate the cavity emission subsequent to nonresonant pulsed excitation. For the ground state emission from the lower energy-momentum dispersion branch we find a two-threshold behavior in the input-output curve where each transition is accompanied by characteristic changes of the in-plane mode dispersion. We demonstrate that the thresholds are unambiguously evidenced in the photon statistics of the emission based on the second-order correlation function. Moreover, the distinct two-threshold behavior is confirmed in the evolution of the emission pulse duration. Our findings show that a comprehensive study of spectral and temporal characteristics of the emission from a semiconductor microcavity can be used to characterize the different emission regimes.