Origin of the Optical Emission within the Cavity Mode of Coupled Quantum Dot-Cavity Systems

The origin of the emission within the optical mode of a coupled quantum dot-micropillar system is investigated. Time-resolved photoluminescence is performed on a large number of deterministically coupled devices in a wide range of temperature and detuning. The emission within the cavity mode is found to exhibit the same dynamics as the spectrally closest quantum dot state. Our observations indicate that fast dephasing of the quantum dot state is responsible for the emission within the cavity mode. An explanation for recent photon correlation measurements reported on similar systems is proposed.

Figure 1

(a) Time integrated emission spectra of pillar $A$ taken at temperatures $T$ between 10 and 50 K. Excitation power $0.25\mu \mathrm{W}$. Dotted curves help following the spectral position of the $X$, $CX$, $XX$, and $M$ lines with temperature. (b) Streak camera images (emission intensity as a function of energy and time) measured on pillar $A$ at $T=10\mathrm{K}$ and $T=40\mathrm{K}$. (c) Emission decay time for $XX$, $CX$, and $M$ lines as a function of $T$ between 10 and 50 K.

Figure 2

(a) Emission intensity as a function of time at $X$ and $M$ wavelengths measured on pillar $B$ at $T=53\mathrm{K}$. The curves have been vertically shifted for clarity. Decay times obtained from a monoexponential fit are indicated. Inset: corresponding streak camera image and PL spectrum. (b) Emission decay time for $X$ and $M$ lines plotted versus $X\mathrm{\text{−}}M$ detuning (bottom axis) and temperature (top axis).

Figure 3

(a) Decay time of the emission within cavity mode ${\tau }_M$ as a function of the emission decay time for the spectrally closest QD state ${\tau }_{\mathrm{QD}}$ measured on seven different devices for more than 30 temperatures. Free parameter linear fit yielding the $1.02\pm 0.08$ slope is shown. (b) The ratio ${\tau }_M/{\tau }_{\mathrm{QD}}$ as a function of $\mathrm{QD}\mathrm{\text{−}}M$ detuning $\Delta$ normalized by mode linewidth ${\gamma }_M$ of each pillar.

Figure 4

(a) Intensity of $X$ (black) and $M$ (red) emission lines measured on pillar $B$. (b) Ratio of emission intensity within the mode to the overall ($X$ plus $M$) emission intensity. The plots are versus $X\mathrm{\text{−}}M$ detuning (bottom axis) and temperature $T$ (top axis).