Modeling of end-pumped electrooptically Q-switched lasers with the influences of thermal effects and spatial mode matching

Abstract

An improved theoretical model of electrooptically Q-switched operation was presented by introducing dimensionless parameters to directly evaluate three characteristic parameters, namely, pulse energy, peak power, and pulse width, which include thermally induced diffraction loss and spatial mode matching between the pump and oscillating modes under the thermal lens effect. An actively Q-switched experimental system with asymmetrical flat–flat dynamically stable resonators was used to validate the theoretical model. The focus depth is fixed by the measurement of thermal focal length with different telescope systems and both the theoretical and experimental results show that spatial mode matching and output power are less sensitive to the depth of focus at a large pump waist size than a small one. Comparisons of output parameters between with and without thermally induced diffraction loss and spatial mode matching show that the current model can perform well in designing actively Q-switched lasers accurately.