光泵三能级激光的全量子理论

本文采用Langevin量子理论处理光泵三能级激光体系。在激光场的光子数不太高时导出一个普适的激光场Van der Pol运动方程。它既包括了非相干和相干泵浦,又包括了强泵浦和弱泵浦情况。若对热库取平均,该方程将给出半经典理论的全部结果。本文的结果表明,激光增益来源于两个基本过程:两个光子过程和两步过程。当泵浦强度大于某阈值时,将出现动态斯塔克效应。激光线宽主要来源于热噪声、真空涨落、激光能级的自发辐射以及自发Raman散射。 关键词：

FULL QUANTUM THEORY OF OPTICALLY PUMPED THREE-LEVEL LASER

The Langevin quantum theory has been used to treat the optically pumped three-level laser system. We derive an equation of motion for laser field in the type of Van der Pol equation when the photon number of the laser field is not too high. It includes not only both incoherent and coherent pumping, but also both strong and weak optical pumping. If an average over reservoir is taken, the equation will give all the semi-classical results. Our results show that the laser gain comes from two basic processes, i.e., a two-photon process and a two-step process. When the pumping strength is larger than some value, the dynamic Stark effect will appear. The laser linewidth is mainly contributed by the thermal noise, the vaecum fluctuation, the spontaneous emissions between the laser levels and the spontaneous Raman scattering.