缓冲气体对光泵远红外激光器能量交换的影响

Effects of Buffer Gas on the Energy Exchange of Optically Pumped NH_3 Far-infrared Laser

基于分子振动弛豫的理论,完善了缓冲气体的作用模型。利用半经典密度矩阵理论与量子力学理论,研究了缓冲气体对光泵远红外激光(FIR)激光过程的作用机理,计算了缓冲气体作用下小型光泵FIR激光器的能量交换过程以及气压等工作参数对输出光强的影响,得出了优化规律,并进行了实验验证。结果表明,适当的缓冲气体可缩短工作气体分子的振动弛豫时间,提高光泵FIR激光器的能量转换效率,使FIR激光信号得到更大的输出。在最佳混合气体比例与最佳工作气体下,可以获得最大的FIR激光信号输出。

Based on the theory of vibrational relaxation, the buffer gas mechanic model was developed. The mechanism and effects of buffer gas on the energy exchange and output power of optically pumped far-infrared (FIR) laser were calculated and studied by semi-classical density matrix theory and quantum mechanics theory. Laser output intensity was calculated and discussed in case of different operating parameters such as operating gas pressure, and the optimization rules were concluded. Finally the theoretical results are verified by the experiments. The results showed that: the vibrational relaxation time could be decreased and the efficiency of energy exchange could be increased when certain buffer gas was added into the laser medium, thus the output power of NH3 FIR laser could be greater. And there existed an optimum ratio of gases mixture and an optimum operating gas pressure, which could make the output power of FIR laser reach maximum.