Temporal monitoring of nonresonant feeding of semiconductor nanocavity modes by quantum dot multiexciton transitions

We experimentally investigate the nonresonant (Delta E > 5 meV) feeding of photons into the optical mode of a two-dimensional photonic crystal nanocavity by quantum dot multiexciton transitions. Power-dependent photoluminescence measurements reveal a superlinear power dependence of the mode emission, indicating that the emission stems from multiexcitons. By monitoring the temporal evolution of the photoluminescence spectrum, we observe a clear anticorrelation of the mode and single exciton emission; the mode emission quenches as the population in the system reduces toward the single exciton level while the intensity of the mode emission tracks the multiexciton transitions. Our results lend strong support to a recently proposed mechanism [M. Winger et al., Phys. Rev. Lett. 103, 207403 (2009)] mediating the strongly nonresonant feeding of photons into the cavity mode.