Control of the pulse width in a diode-pumped passively Q-switched Nd:GdVO4 laser with GaAs saturable absorber

Different techniques to control the pulse width of a diode-pumped passively Q-switched Nd:GdVO4 laser with GaAs saturable absorber have been studied. It is shown that varying the positions of the saturable absorber in the laser axis and the pump beam waist in the gain medium provides an efficient means to control the pulse width. A rate equation model is introduced to theoretically analyze the results obtained in the experiment, in which the Gaussian spatial distribution of the intracavity photon density, the longitudinal variation of the photon density and the pump beam spatial distribution are taken into account. The numerical calculations of the rate equations are consistent with the experimental results.