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采用谐振腔内插入声光调制器的方法进行了小型CO2激光器的调Q实验,并根据影响激光器输出的诸多因素,利用调Q脉冲激光器速率方程对该激光器输出的主要技术参数进行了理论计算,据此提出了声光调QCO2激光器优化设计的途径和方法。设计制成的声光调QCO2激光器获得峰值功率超过4000 W,激光脉冲宽度为180 ns,与理论计算基本一致。激光器脉冲重复频率调节范围1 Hz~100 kHz。理论分析和实验结果均证明,调Q晶体中超声场的渡越时间并不会影响输出激光的脉冲宽度,因此无需在腔内插入光学透镜进行光束直径的压缩变换;渡越时间的影响只是体现在延长了激光脉冲的建立时间上;激光器的最佳工作频率在1 kHz左右,这与CO2分子0001能级大约1 ms的辐射寿命相匹配,当频率超过1 kHz时,激光的脉冲宽度随着频率的增加而开始加宽。激光器通过光栅选线的设计方式实现了9.2~10.8μm的全波段波长调谐,测得激光输出谱线超过60条。
The Q-switched experiment of a small CO2 laser was carried out by inserting the acousto-optic modulator in the resonant cavity. According to many factors affecting the output of the laser, the main technical parameters of the laser output were theoretically calculated by using the Q-switched pulsed laser rate equation, Based on this, the ways and methods of optimizing the design of acousto-optic QCO2 laser are proposed. The designed acousto-optic QCO2 laser achieves a peak power of more than 4000 W and a laser pulse width of 180 ns, which is basically consistent with the theoretical calculation. Laser pulse repetition frequency adjustment range 1 Hz ~ 100 kHz. Theoretical analysis and experimental results show that the transit time of the ultrasonic field in the Q-switched crystal does not affect the pulse width of the output laser, so there is no need to insert an optical lens in the cavity to compress and transform the beam diameter. The effect of transit time is only reflected The laser pulse has an optimum working frequency of about 1 kHz, which is compatible with the radiation life of the 0001 of the CO2 molecule at the energy level of about 1 ms. When the frequency exceeds 1 kHz, the pulse width of the laser varies with Frequency increases and began to widen. The design of the laser line through the grating to achieve a 9.2 ~ 10.8μm wavelength tuning of the whole band, the measured laser output spectrum of more than 60 lines.