激光脉冲前后沿相干叠加对多程放大的影响

针对多程放大过程中激光脉冲经腔镜折返前后沿交叠的问题,建立了激光脉冲在增益介质中前后沿相干叠加放大的物理模型.理论分析表明,脉冲前后沿完全相干叠加形成驻波场,使得反转粒子数出现烧孔效应,影响输出脉冲的增益和波形.基于此物理模型,模拟计算了脉冲在多程放大过程中波形的演化,比较了不交叠、完全非相干叠加和完全相干叠加三种情况下对放大器的增益和对脉冲波形的影响.为高功率固体激光器的设计提供指导.

Effect of laser coherent superposition in multi-pass amplification process

Aming at the coherent superposition of laser pulse reflected from the cavity mirror in multi-pass amplification process, a physical model for describing the amplification of coherent superstition of the rising part and the falling part of the pulse in a gain medium is established. According to theoretical analysis, standing wave is formed by the coherent superposition of the rising part and falling part of the pulse. The inversion population density shows up the effect of hole-burning by the standing wave, and the gain and pulse shape are affected. Based on this physical model, three conditions, i.e., no superposition, coherent superposition, and incoherent superposition are compared. This study will provide the instructions for high power solid laser design.
Keywords： multi-pass amplification cavity mirror coherent superposition gain saturation