Study On Pulsed LD Acousto-Optic Q-Switched Pumped Tm: LuAG Laser

The wavelength of Tm:LuAG Q-switched laser pumped by pulsed LD is 2.023μm. The laser band is in the safety band of human eyes and closed to the atmospheric window. 2μm laser has a very important application both as the laser light and in military, medical or other fields. This paper from theory and experiment to study on pulsed LD acousto-optic Q-switched pumped Tm: LuAG laser in order to obtain the laser of high single pulse energy and repetition frequency.First of all, Based on the three energy level structure of Tm:LuAG,we established and solved the rate equations of LD pumped Tm:LuAG crystal. We derive the threshold value ofpumping,peak power,energy of single pulse,the width of pulse and other parameter expression to do the numerical simulation. What we do is to lay the theoretical foundation for experiment.Secondly based on the thermal model of the single-ended bonding Tm:LuAG crystal we simulated the range of the change of thermal focal length and the transient temperature. We talk about the impact of thermal focal length and temperature of the Tm:LuAG crystal from the length and the doping concentration,the pumping of pulsed LD,the pumping power and other parameters in order to lay the theoretical foundation for choosing the crystal and design the cavity.Thirdly design the laser system of pulsed LD acousto-optic Q-switched pumped Tm: LuAG and confirm the parameters of LD,Q-switched crystal,Tm: LuAG crystal and the cavity. We put forward using two pulse LD intermittent pumping two single-ended bonding crystal to ease the thermal effect of crystal. And this way can make the compensation of thermal effect without insert redundant element and improve the stability of cavity.Finally we carried on the experiments of pulsed LD acousto-optic Q-switched pumped Tm: LuAG laser. We measured the output characteristics of 790 nm LD and the thermal focal length of Tm:LuAG crystal. The results of the experiment:the acousto-optic Q-switched laser with the repetition frequency is 100 Hz,the single pulse energy is 2.25 mJ,the width of pulse is 5000μs,the center wavelength of laser is 2023.0nm,the quality of beam is M2x=1.07,M2y=1.30.