小型光泵远红外激光的放大过程

利用三能级系统的密度矩阵方程，通过迭代法计算了小型光泵ＮＨ３分子远红外激光器（ｍｉ－ｎｉ－ＮＨ３－ＯＰＦＩＲＬ）的介质增益Ｇｓ沿激光管的变化规律以及远红外信号光强Ｉｓ沿激光管的放大过程。计算表明激光管有激活区和饱和区，对一定管长的ｍｉｎｉ－ＮＨ３－ＯＰＦＩＲＬ，在一定范围内工作气压的提高，主要使Ｇｓ的峰值增大，同时使激活区缩短，考虑散射损耗和自吸收效应后，Ｇｓ峰值的提高对总的输出光强贡献不大。而泵浦光强Ｉｐ０的增大，有利于激光管内的介质沿光轴方向均匀激活，从而提高总的输出光强。另外，信号频偏对ｍｉｎｉ－ＮＨ３－ＯＰＦＩＲＬ的激光放大过程有较大的影响

Amplifying Process of Miniature Optically Pumped Far Infrared Laser

Via solving density matrix equations of the three level system, the medium gain Gs and output power density Is along the sample tube in a miniature optically pumped NH 3 molecular far infrared laser (mini NH 3 OPFIRL) were calculated by means of the iteration method. The calculation results showed that the laser tube had an active region and a saturation region. For the mini NH 3 OPFIRL with a definite tube length, in a certain range the rise of operating gas pressure mainly resulted in an increase of peak value of Gn and shortening of the active region. Considering the scattering loss and the self-absorption effect, the increase of peak value Gn was not important to the laser output intensity. But, the rise of pumping laser intensity Ip0 was advantageous to the homogeneous activation along the light axis of the medium, which enhanced the total output power. Meanwhile, the signal frequency detuning obviously affected the amplifying processes in the mini-NH3-OPFIRL.