Multiple-pulse microcavity lasing from an optically induced confinement

Coupled electron-hole-photon systems in semiconductormicrocavities have been a platformfor studies of laser dynamics and nonequilibrium cooperative phenomena in solid states. Here, we report the observation of multiple-pulse lasing in optically induced confinement in a highly photoexcited semiconductor microcavity at room temperature. The spatially photomodulated refractive index changes enable an additional lateral photonic confinement, and discrete transverse modes result. Temporally and spectrally resolved measurements of the radiation reveal multiple sub-10-ps pulsed radiation commencing in order from high-to low-energy modes. Under a circularly polarized optical pumping, the highenergy mode emerges within 10 ps after the pulsed excitation and has a near-unity circular polarization.We attribute the observed cooperative effects to light-induced correlated e-h pairs in a high-density plasma and their effective coupling to discrete transverse modes in the spatially photomodulated optical confinement.