| The high pulse energy and high average power Q-switched lasers in 2 ?m region are widely used in the fields of lidar,remote sensing,medical and industrial processing,and can be used as an important light sources for generating of 3~5 ?m mid-infrared light via optical parametric oscillation.At present,the main methods of generating 2 ?m near-infrared laser include lasers based on rare-earth doped gain media,nonlinear frequency conversion,semiconductor lasers,free electron lasers and so on.Among them,lasers based on rare-earth doped gain media as a direct and efficient technical means have attracted much attention.Focusing on the 2 ?m region solid-state laser,the Tm3+ doped solid-state acousto-optic Q-switched and electro-optically Q-switched systems were studied from the theoretical and experimental aspects.Q-switched technology,one of the important methods to obtain pulse laser output,that is,through some means to make the loss of cavity change with certain rules,so that output laser launch in the form of pulse.The development of Q-switched technology greatly increased the peak power of pulse laser and narrowed the pulse width.In this paper the theoretical work was mainly focused on the study of the output pulse laser characteristics of Tm:YAG actively Q-switched laser.The quasi-three-level Tm:YAG actively Q-switched laser rate equation model was established,the relationship between the peak power,the pulse energy,the pulse width and the repetition frequency of the Q-switched laser was deduced,and how these three quantities change with the repetition frequency was described.We also simulated the effects of output mirror transmittance and cavity length on the output pulse.The numerical simulation results have provided theoretical guidance for the experiment.Experimental research including:1.Acousto-optic Q-switched Tm:YAG slab laser system was demonstrated.When the pump power was 83.6 W,the highest output power of 25.4 W was obtained and the corresponding slope efficiency was 41.2 %.The output characteristics of 1 kHz,5 kHz,10 kHz were measured under acousto-optic Q-switched lasers,at repetition frequency of 1 kHz,the maximum average power of 20.7 W was obtained,the peak power was 246 kW,and the narrowest pulse width was 84 ns,corresponding to a slope efficiency of 36.1%.This is believed to be the highest average power and slope efficiency in 2 ?m Q-switched solid-state lasers.2.Short pulse diode-pumped Tm:YAG slab laser electro-optically Q-switched by RbTiOPO4 crystal was demonstrated.The optimal quarter-wave voltage of 1.05 kV of the RTP electro-optical Q-switching was determined at repetition frequency of 5 kHz.The insertion loss caused by the polarizer and the electro-optical crystal was analyzed.When the pump power was 43.8 W,the highest output power of 13.2 W was obtained and the corresponding slope efficiency was 38.7 %.The maximum average power obtained at the repetition frequency of 1 kHz was 7.5 W,the narrowest pulse width of 58 ns was obtained,the peak power was 125 kW,and the corresponding slope efficiency was 21.7%.This result is believed to be the maximum average power and slope efficiency obtained in 2 ?m Tm-doped solid electro-optical Q-switched lasers. |
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