Optimization of pumping pulse duration for a pulsed diode pumped q-switched laser

Based on the theory of rate equations for a pulsed diode pumped Q-switched laser, optimum pumping pulse duration is analysed theoretically by taking account of pump power level, output mirror transmission and intracavity loss In Q-switched laser. The results show that, when the transmission of output mirror is 20%, the intracavity loss is 0.05, the optimum pumping duration is 1-1.5 times fluorescence lifetime of Nd:YAG at the pump power level is 1-3 times of the threshold power; the optimum pumping duration is about half the fluorescence lifetime or even less, when the pump power is more than 7 times threshold power. At the same pumping pulse energy level, the higher energy conversion efficiency can be obtained at the shorter pump duration (that is the higher pump power).