准连续可调的NH_3分子光泵亚毫米波激光

Quasi-continuously Tunable Optically Pumped NH_3 Molecular SMMW Lasers

以NH_3分子气体为工作物质,对CO_2激光和微波同时作为泵浦源的光泵亚毫米波激光系统的密度矩阵方程的求解,获得光泵激光器的频率特性和增益特性。理论计算结果表明:利用光泵激光中的超喇曼过程,改变微波频率,可以产生频率准连续可调的亚毫米波信号;利用谱线的压力增宽,调节激光的腔长,改变其纵模频率,也可以获得准连续可调的亚毫米波信号。

In this paper, the semiclassical density matrix treatment was applied to four-level system for optically pumped NH_3 molecular submillimeter wave (SMMW) lasers, which was pumped by CO_2 laser and microwave simultaneously. The hyper-Raman process in the laser system was studied and the frequency characteristics and gain characteristics were obtained by numerical calculations. It was found that a quasi-continuously tunable SMMW signal could be achieved in the hyper-Raman lasers by tuning the input microwave frequency. In another way, by using pressure broadening effect of the spectrum and the quasi- continuously tunable SMMW signal can also be obtained by increase the operating gas pressure of the laser and adjusting the length of the cavity.