Experiment research of high repetition rate acousto-optic Q-switched fiber laser under air cooling

In order to obtain the air cooling high repetition fiber laser with stable power, an acoustic-optical Q-switched all-fiber laser with master oscillator power amplifier structure was studied. The oscillator used the scheme of acousto-optic Q-switched with a pair of fiber Bragg grating as laser cavity mirrors. Pumped by 915nm laser diodes, 1064nm laser pulse output was acquired with adjustable repetition rates from 10kHz to 130kHz. Through two-stage double clad large mode area fiber amplifier, 101W output power was obtained with 328.1ns pulse width. The 3dB optical spectrum width of fiber laser was 0.6nm. Optical-optical efficiency of the second amplifier stage was 69%. The total optical-optical efficiency of laser was 62.7%. The distortion cause of long width seed pulse created by acousto-optic Q-switched through the amplification was studied. The experimental results show that pumped by 915nm laser diodes, the long-term stability of output power is proved to less than 2% under air cooling.