Figure 3.

Micro-PL spectrum under non-linear excitation recorded at 4.2 K. The excitation wavelength is 814 nm, and the average excitation power is 6.3 mW at a repetition frequency of 19 MHz. The inset shows the time-resolved emission spectrum of the QD whose emission is at 437.8 nm. The continuous line is a least-square fit with single exponential