Abstract: Presented herein is the use of the fiber-pigtailed LiNbO3 electro-optical modulator with the Mach-Zehnder structure as the active Q-switching element. The laser is composed with an electro-optic modulation as Q-switch, Yb-doped fiber (peak absorption coefficient at 974 nm is 110 dB/m) as the gain medium, and pumped by semiconductor laser of 974nm wavelength. The way, modulating periodically cavity loss by the electro-optical modulator, can realize Q-switching action, to obtain the stable Q-switched pulses. The stable pulse can be obtained when the modulation frequency was adjusted from 50 Hz to 88 kHz. The laser pulse with maximum peak power of 5W, pulse width of 246ns is obtained, when the modulation frequency is 1 kHz.

Key words: laser techniques; active Q-switch; M-Z electro-optical modulator; multi-peak phenomenon