研究了谐振腔式圆片激光器中放大的自发辐射（ASE）和寄生振荡的物理特征及一些抑制措施的效果。使用解析方法分析了圆片介质中本征寄生模式，指出非平庸的色散关系只允许有限数目稳态纵寄生模存在，使其与主激光进行纵模竞争时处于不利地位。研发了一套数值模拟方法对ASE、寄生振荡和主激光的耦合成长特性进行理论研究,分析了它们之间横模竞争的特点，指出弛豫振荡在ASE效应中扮演重要的角色。并且从实验和理论两方面研究了ASE吸收包边导致的热加载不均匀问题。

Amplified spontaneous emission(ASE) and parasitic oscillation in laser resonators exhibit distinct physical properties. An analytic method is employed to find eigenmodes of disk medium. These modes processes some non-trivial dispersion relations, which allow few stable longitudinal modes only. It decreases amplifying rate of parasitic oscillation in mode competition with main laser. A numerical model is further proposed to perform (3+1) dimensional simulations. Ray tracing method, together with finite-difference in time domain and Fox-Li type iteration, are used to solve a set of coupled equations. Transverse mode competition between ASE/parasitic oscillations and main laser increases threshold to establish laser oscillation and decreases output power as well. Time evolution of laser output exhibits a strenuous relaxation oscillation, in which ASE plays a role of strong damping. Heat generation in a Nd:YAG thin disk laser composite with an undoped anti-ASE cap and a side ASE absorber is investigated. Heat load unbalance among three different regions induces a large transverse temperature inhomogeneity is observed experimentally.