Novel use of GaAs as a passive Q-switch as well as an output coupler for diode-pumped infrared solid state lasers

Q-switched operation is very common and important for diode- pumped solid-state lasers. In this paper, we reported a novel use of GaAs wafers as Q-switch elements as well as output couplers for DPSS lasers. A pulse duration of 2.6 ns at the wavelength of 1064 nm was obtained from a diode- pumped and passively Q-switched Nd:YVO4 laser using a piece of GaAs wafer as the saturable absorber as well as the output coupler. The transmissivity and the absorption coefficient of different wafers were studied. The experimentally measured results indicated that the transmissivity of different GaAs wafers varied from as low as approximately 32% to as high as approximately 75%. It was found that some of those wafers showed Fabry-Perot effect and it could affect the effective transmissivity and produce lower transmission, and thus shorten the pulse duration and stabilize the laser operation.