Origin of the emission within the cavity mode of coupled quantum dot -cavity devices

Although quantum dots (QDs) are usually considered as atomic like emitters, many features of coupled QD-cavity systems cannot simply be described in the Jaynes-Cumming framework. Indeed, it has been widely observed that most of the emission arises from the cavity mode even for large spectral detunings between the QD and the optical mode.

We have investigated the origin of the emission within the cavity mode of deterministically coupled QD-pillar cavities. Time resolved photoluminescence measurements carried out in a wide range of detunings show that the emission within the cavity mode presents the same dynamics as the spectrally closest QD state. When two states of the same QD are equally detuned from the cavity mode, the emission within the mode presents the same decay as the spectrally wider QD state. These observations show that fast dephasing processes of the QD state leads to an efficient emission within the cavity mode. Our results also provide an explanation for recent photon correlation measurements reported on similar systems.

Figure: (left): SEM image of deterministically coupled QD cavity systems. (Centre): Emission of a coupled QD-cavity system as a function of time and energy. XX,X, CX , and M lines correspond to the emission at the biexciton, exciton, charged exciton and cavity mode energy. (Right): Measured decay time within the cavity mode as a function of the decay time of the spectrally closest quantum dot state. The strong correlation between the two decay time for a very large range of experimental conditions prove that the emission within the cavity mode arises from the QD state, assisted by dephasing processes.

Contacts :

Pascale Senellart and Paul Voisin (Optics of Semiconductor nanoStructures research team)

Further reading

J. Suffczynski et al., Phys. Rev. Lett. 103, 027401 (2009).