Analytical and experimental studies on the diode-pumped, simultaneously Q-switched and mode-locked c-cut Nd:GdVO 4 /KTP green laser with LT-GaAs absorber

. A diode-pumped passively Q-switched mode-locked (QML) intracavity frequency doubled c-cut Nd:GdVO 4 /KTP green laser with a LT-GaAs saturable absorber is presented. More than 90% modulation depth for the mode-locked green pulses has been achieved. Using the hyperbolic secant function methods, a developed rate equation model for Q-switched and mode-locked lasers considering the Gaussian spatial distribution of the intracavity photon intensity, the influences of continuous pump rate, the upper state lifetime of the active medium, and the excited-state lifetime of the saturable absorber, was proposed. With this developed model, the theoretical results are in good agreement with the experimental results and the width of the mode-locked green pulse was estimated to be about 380 ps.