Fig. 1. (Color online) (a) Experimental setup. A fiber-pigtailed distributed feedback (DFB) laser diode is driven by DC and AC electric pulse from pulse generator (PG). The electrical pulse from pulse generator (PG) was amplified by RF Amplifier. The operation temperature of the DFB laser is regulated by a temperature controller driving the built-in TEC. (b) Temporal profiles of the laser pulses for different DC currents. (c) Intensity fluctuation of a GSSL as a function of the DC driving currents.

Fig. 2. (Color online) (a) Intensity correlation distribution between adjacent pulses "T" and "X" under different driving currents. (b) Intensity correlation distribution between pulses "T" and "Y" under different driving currents. (c) Intensity correlation distribution between pulses "T" and "Z" under different driving currents. (d) Auto-correlation function of intensity between adjacent pulses with different intervals.

Fig. 3. (Color online) Calculated temporal behavior. (a)−(e) The evolution of photon and carrier density from a GSSL as the driving currents increase. The threshold carrier density is depicted as a horizontal dash-dot line. (f) The autocorrelation function for adjacent pulse with different intervals.

Fig. 4. (Color online) The influence of light pulse intensity fluctuation on SKR under different driving currents.