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采用旋转光栅法实现了声光调Q CO_2激光器可调谐脉冲激光输出。理论分析了CO_2激光波长调谐特性,发现调节各支谱线腔内损耗是实现激光波长调谐的有效方法。进而理论计算了特定设计波长闪耀光栅的衍射效率与激光波长间的关系,结果显示光栅调谐的激光谱线自准直角与光栅闪耀角一致时具有最高的衍射效率。采用闪耀角分别为31.97°(闪耀波长10.59μm)和28.71°(闪耀波长9.60μm)的光栅实验研究了声光调Q CO_2激光器波长调谐特性,分别获得了65条和75条激光谱线。实验结果显示:光栅设计闪耀波长处于弱激光增益分支时可获得更多条激光谱线,该实验与理论计算结果相符。在脉冲重复频率为1 k Hz时,获得10.59μm激光脉冲宽度为160 ns,平均功率4.2 W,脉冲峰值功率26.25 k W,且稳定性良好。
The tunable pulse laser output of acousto-optic Q-switched Q-CO_2 laser is realized by the rotating grating method. The wavelength tuning characteristics of CO_2 laser are analyzed theoretically. It is found that adjusting the cavity loss in each branch line is an effective method to realize laser wavelength tuning. Furthermore, the relationship between the diffraction efficiency of the blazed gratings and the laser wavelength is calculated theoretically. The results show that the gratings have the highest diffraction efficiency when the laser line is aligned with the grating blaze angle from the collimation angle. The grating tunings of 31.97 ° (blazing wavelength 10.59μm) and 28.71 ° (blazing wavelength 9.60μm) were used to study the wavelength tuning characteristics of the acousto-optic Q Q-switched laser and 65 and 75 laser lines were obtained. The experimental results show that more laser lines can be obtained when the grating design is at weak laser gain, and the experiment is in good agreement with the theoretical calculation. When the pulse repetition frequency is 1 k Hz, the 10.59μm laser pulse width is 160 ns, the average power is 4.2 W, the pulse peak power is 26.25 k W, and the stability is good.