Numerical investigation into the impact of Q-switch rise time on the output pulse characteristics in an actively Q-switched ytterbium-doped fiber laser

We report the results of our theoretical investigation into the impact of the Q-switch rise time on three key parameters of the output pulses in an actively Q-switched fiber laser, namely the multipeak phenomenon, pulse energy, and pulse peak power. Our investigation is conducted over a Q-switch time range of up to 12 times the cavity round-trip time (τround). We show that when a longer Q-switch rise time is applied to the cavity, a trade-off exists between multipeak phenomenon suppression and pulse energy maintenance. The results show that the Q-switch rise time (τrise) for the efficient suppression of multipeak phenomenon without loss of pulse energy varies, depending on the cavity parameters. In an exemplary, actively Q-switched fiber laser operating under the condition of a repetition rate of 15 kHz, τrise is estimated to be approximately five times larger than τround.