| The wavelength of the wind detection radar light source is required to be about 2?m,and the central wavelength of the output of the Tm:Lu YAG laser is 2020 nm,which can meet its needs.At the same time,compared with the Tm:YAG,its output wavelength deviates more from the absorption peak of water,and its cost is cheaper than that of the Tm:Lu AG.Therefore,Tm:Lu YAG laser has greater development potential,and it can also be used in medical operation,laser ranging,material processing and cutting and other fields.The main contents of this paper are as follows:Theoretically,the absorption spectrum of Tm:Lu YAG crystal is analyzed,and it is confirmed that it has a strong absorption peak at 785 nm,which can be pumped by a LD with a central wavelength of 785 nm.By analyzing the energy level structure of Tm3+ in Tm:Lu YAG crystal,the rate equation of CW and pulse pumped Tm:Lu YAG laser is established and the rate equation of CW and pulse pumped Tm:Lu YAG acousto-optic Qswitched laser is established.The doping concentration of the crystal is 3.5%.The analysis results show that the threshold power of CW pumped Tm:Lu YAG laser is 3.4W when it is running freely,and the output power is 4.7W when the pump power is 15 W.When the repetition frequency is 100 Hz and the pumping power is 9W,the single pulse energy of CW pumped Tm:Lu YAG acoustooptic Q-switched laser is 3.39 m J When the pulse pumped Tm:Lu YAG laser operates freely,the threshold energy is 16 m J,and when the injected energy is 150 m J,the laser output of 64 m J can be obtained.When the repetition frequency is 100 Hz and the injected energy is 80 m J,the single pulse energy of pulse pumped Tm:Lu YAG acoustooptic Q-switched laser is 2.53 m J.In the aspect of crystal thermal effect,the thermal model of Tm:Lu YAG crystal with continuous and pulse pumping double end bonding is established,and the temperature distribution inside the crystal is simulated.From the simulation results,it can be seen that the pulse pumping mode can alleviate the thermal effect of the crystal.In order to design an optically stable resonator,the thermal focal length values of Tm:Lu YAG crystal under different pumping modes are calculated and verified by experiments.In the aspect of experiment,the output characteristics of CW and pulse LD end pumped Tm:Lu YAG laser and the acoustooptic Q-switched output characteristics of CW and pulse LD end pumped Tm:Lu YAG laser are studied.The threshold value of CW pumped Tm:Lu YAG laser is 3.7W.When the pump power is 15 W,the maximum output power is 3.7W,and the slope efficiency is 30.7%.When the pumping power is 9.12 W and the repetition frequency is 100 Hz,the maximum pulse energy of CW pumped Tm:Lu YAG acoustooptic Q-switched laser is 3.07 m J and the pulse width is 100 ns.When the pulse pumped Tm:Lu YAG laser is running freely,the threshold value is 20.8m J.At the repetition rate of 100 Hz,pulse width of 5ms and injection energy of 94.7m J,the maximum output energy of Tm:Lu YAG laser is 27.1m J and the slope efficiency is 36%.When the injected energy is 80.8m J and the repetition frequency is 100 Hz,the maximum pulse energy of pulse pumped Tm:Lu YAG acoustooptic Q-switched laser is 2.28 m J and the pulse width is 141.5ns.The experimental results are basically consistent with the theoretical simulation results... |
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