Optimization of the passively Q-switched laser with a novel central semiconductor saturable absorption mirror (C-SESAM)

The diode-pumped passively Q-switched laser, realized with a novel central semiconductor saturable absorption mirror (C-SESAM), can obtain much higher repetition rate and shorter pulse duration which have been proved theoretically and experimentally. Therefore, it is essential to optimize this kind of lasers to achieve many of the desired properties. The normalized rate equations are solved numerically, when the direct band-gap absorption of the InGaAs thin layer, the single-photon absorption (SPA) and two-photon absorption (TPA) processes of GaAs substrate are simultaneously considered. Some new normalized parameters are introduced and the key parameters of an optimally passively Q-switched laser are determined, including the optimal normalized coupling parameter and the optimal normalized saturable absorber parameters, which can maximize the output energy. A group of general curves are generated, and sample calculations for a diode-pumped Nd3+:YVO4 laser with a novel central semiconductor saturable absorption mirror (C-SESAM) are presented to demonstrate the use of the curves and the relevant formulas.