The analyses given in this paper to quasi - three - level for 946 nm laser are complete . the relation between 946 nm laser transmission and optimal crystal length has been derived from the rate equations describing the population inversion and the photon density in the laser cavity in the steady - state case . the minimal claims to coating have been given on the base of contrasting 946 nm transmission with 1064 nm transmission in the condition of different cavity losses and how the pump beam radius in the laser crystal and optimal crystal length affect the laser threshold and output power of 946 nm laser has been given as well 对产生946nm谱线的准三能级结构给出了较为完整的分析，利用激光谐振腔处于稳态时的速率方程，导出了准三能级nd ： yag946nm起振时，透射损耗与最佳激光晶体长度的关系，在与1064nm透射损耗相比较的基础上，给出了不同的腔损耗情况下的最低镀膜要求，并且给出了激光阈值、输出功率和最佳激光晶体长度及泵光光斑大小的关系，这为设计室温下高效运转的946nm激光器的提供了理论基础，这种分析方法对研究此类低增益，准三能级或三能级激光系统输出特性有借鉴意义。
