研究了一台端面抽运的Nd:YAG板条激光放大器，采用低掺杂、键合的Nd:YAG板条晶体和3通放大结构，实现功率330 W，光束质量M2x=1.23，M2y=1.73的激光输出。采用4f像传递系统，有效减小了板条入口的切光损耗，并实现了板条内能量的均匀提取。根据1、3通放大功率计算了相应的增益系数，并简要分析了多通放大结构对放大自发辐射(ASE)的抑制作用。

An end pumped Nd:YAG slab laser amplifier is presented. Low doped and composited Nd:YAG slab is used to obtain continuous wave output power of 330 W and beam qualities of M2x=1.23, M2y=1.73 under the 3 passes amplification stucture. Taking advantage of 4f image system, the loss from light cutoff is reduced and the uniformed energy extraction is realized. In addition, gain coefficients are calculated by the output power of single and multiple pass amplifications. It is also investigated that the multiple amplification structure is good to restrain the amplified spontaneous emission.