Master oscillator power-amplifier (MOPA) configuration was widely used in high-power laser system. In order to find the optimal ratio of oscillator to amplifier, influences of this ratio on the near-field intensity distribution and the output power were studied. Fast Fourier transform method was used to calculate the near-field intensity distribution and the powers at the ratios of 1:4, 1:1 and 2:1. The simulation results indicated that when the total volume of the gain is constant, the output power of the oscillator increases with the ratio. The results also showed that the diffraction influence increases with the length of the amplifier. It was noted that the ultimate output power of the laser system was affected by the ratio of oscillator to amplifier intensity, when the laser was run at the same gain distribution, saturable intensity, amplification of the unstable oscillator, size of the whole laser and various losses of the cavity.% 主振功率放大型装置在高能激光器中有着广泛的应用,在增益体积和沿光轴方向增益长度一定的情况下,为了得到高能化学激光器主振部分和放大级部分的最佳比例,研究了不同振荡放大比对输出光束的近场强度以及最终输出功率的影响。使用快速傅里叶变换的算法经过迭代计算得到了1：4,1：1,2：1三种振荡放大比情况下的近场光束强度分布,并计算了其强度分布均匀性及最终输出功率情况。计算结果表明：采用MOPA结构的氟化氘化学激光器,振荡放大比越大,主振荡部分输出的能量越高,谐振腔内功率密度越大,对腔内镜片的承受能力要求越高；而振荡放大比越小最终输出光束的衍射放大效应越明显,对光束质量越不利。在本文条件下,计算结果还表明,振荡放大比对功率会产生影响,存在一个最佳的比例使得输出功率最大。振荡放大比对输出功率的影响随主振部分输出耦合率,光路中的各种损耗,增益的规模等多种参数的不同而变化,工程运用中可根据具体参数进行计算。
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