Physical Review B
Real-time analysis of the optical response of cavity bipolaritons: Four-wave mixing and dynamics of formation
Hisaki Oka, Hajime Ishihara
Abstract
We theoretically investigate the four-wave mixing (FWM) of a biexciton in a microcavity in the framework of cavity bipolariton. Cavity bipolaritons are stably formed in the strong-coupling regime with an exciton-cavity coupling comparable to the biexciton binding energy. The FWM signal obtained from our bipolariton model, where the biexciton and unbound two-exciton states form a complete system, agrees well with the experimental data [Baars et al., Phys. Rev. B 63, 165311 (2001)]. A strong FWM signal is obtained when a cavity bipolariton is formed by a superposition state of a biexciton and unbound two-cavity-polariton states. We also analyze the dynamics of the formation of biexciton and cavity polaritons by numerically solving the optical master equation in time domain. Efficient excitation of cavity bipolariton requires a specific pulse duration and/or pulse delay so that two-cavity polaritons are formed before the biexciton is excited.