Concurrent Passive Mode-Locked and Self-$Q$-Switched Operation in Laser Systems

Concurrent passive mode-locked and self-$Q$-switched operation of laser devices is modeled using the complex cubic-quintic Ginzburg-Landau equation. Experimental observations use a passively mode-locked fiber ring laser with a waveguide array as a fast saturable absorber. The shape of each individual self-$Q$-switched pulse and the periodic trains of pairs of such pulses are in a good qualitative agreement with the numerical results.

Figure 1

(a) A sequence of DSs within a SQS pulse. The vertical axis corresponds to the maximal intensity $|\psi {|}^2$ of each DS. Inset: pulse profiles of the DS pulses at the maximum (red solid line) and minimum (blue dashed line) of the $Q$-switched pulse. (b) The same sequence in a longer timescale reveals the train of SQS pulses. The light blue area corresponds to the portion of the train shown in (a). (c) A sequence of SQS pulses for the set of parameters that are shown inside the figure.

Figure 2

(a) Bifurcation diagram for maximal $Q$ values of SQS pulses when cubic gain $\epsilon$ changes. The rest of parameters, shown within the plot, are fixed. The wave profiles for the two values of $\epsilon$ marked in (a) by dashed cyan vertical lines are shown in (b) and (c).

Figure 3

Schematics of (a) experimental setup, (b) waveguide array, and (c) typical shape of a SQS pulse in the experiment.

Figure 4

Experimentally observed SQS pulses for five different pump powers, namely (a) 995.8 mW, (b) 1001.1 mW, (c) 1054.2 mW, (d) 1107.3 mW and (e) 1160.5 mW. Timescales and relative intensities are shown in the figure. Individual DSs are not resolved in the scale of this plot.