Sub-nanosecond micro laser passively Q-switched by a GaAs saturable absorber

A Nd:GdVO4/GaAs passively Q-switched laser has been demonstrated based on a microchip design. Under high pump power, the high optical intensity inside the laser cavity triggered the two photon absorption of GaAs, and the pulse duration was shortened to sub-nanosecond level. The shortest pulse of 690 ps was obtained, which we believe is the shortest pulse ever generated with a pure GaAs saturable absorber. The maximum average output power, highest repetition rate, largest pulse energy, and highest peak power were 1 W, 190 kHz, 7.5 μJ, and 10.8 kW, respectively. The results indicated that GaAs is a promising passively Q-switched saturable absorber and still has potential to explore.