Abstract

We report the coexistence of low threshold lasing in the strong coupling (SC) regime in a high-quality semiconductor microcavity under quasi -resonant optical pumping. A sharp laser mode splits from the low polariton (LP) branch and approaches the bare cavity mode frequency as the pumping increases. The laser threshold is achieved fro m low density localized exciton states, which are weakly coupled to the cavity mode. The appearance of this quantum-dot-like lasing mode (QDM) distinguishes quantum well excitons into those, which are strongly coupled and those , which are weakly coupled with the resonant light mode, and reveal the difference in their optical properties under the same optical excitation conditions. These experimental observations contradict current theories that assume Rabi transiti on to be a second order-like phase transition of the system.

© 2003 Optical Society of America