High-average power Q-switched operation of a Nd:YAG rod laser

Summary form only given. Ranging from fundamental physics to the engineering field, high-power diode-pumped solid-state lasers are attractive light sources for various applications. In particular Q-switched operation, used to generate high peak power IR output or green output, is important for material processing, energy applications and environment measurements. It is known that efficient-operation in the Q-switched regime requires a repetition rate higher than the inverse of the medium spontaneous fluorescence lifetime. But in the condition of continuously pumping with fixed power, the pulse duration increases and the pulse peak-power decreases. A way to shorten the pulse duration is to shorten the resonator length as much as possible. This solution is suitable for miniature lasers, but very difficult to fulfil in a high-power system, because intracavity optical elements must be used, as example to optimize the laser-beam spot-size or to compensate for thermal aberration induced by pumping. Another way to shorten the pulse duration is to increase the pump power and increase the gain in the active medium. Our approach to these problems is a quasi-continuous pumping regime which increases gain in the active medium under the fixed condition of thermal effects. We report our results on a high-average power Q-switched Nd:YAG rod laser which is quasi-continuous pumped.