Fig. 1. Experimental setup of actively Q-switched Er³⁺-doped ZBLAN fiber laser using LGS crystal as an electro-optical modulator; the inset shows the cross section of the fiber.

Fig. 2. Measured pulse width, output power, and peak power versus the pump power at an 18 kHz repetition rate; inset, single-pulse envelopes at various pump powers.

Fig. 3. Output performance for Q-switched fiber laser at an 18 kHz repetition rate and 2.8 W pump power. (a) Typical spectrum for the pulses, and (b) RF spectrum with an SNR of 52 dB; inset, output power stability over a 1-h period.

Fig. 4. Q-switched pulses with respect to the repetition rates from 1 to 18 kHz under 1.0 W pump power. (a) Measured pulse width and average power; (b) calculated pulse energy and peak power.

Fig. 5. Oscilloscope trace of the Q-switched pulses at 1, 10, and 18 kHz repetition rates, measured within a sweep range of 5 ms.