为了抑制受激布里渊散射效应, 提高单频窄线宽种子源的放大功率, 采用主振荡功率放大器结构, 并对光纤长度、纤芯直径和抽运参量进行优化, 实现了42W的1064nm信号光输出。实验中, 一级放大采用914nm半导体激光器作为抽运源, 增益光纤芯径10μm, 长度8m; 二级放大采用976nm半导体激光器作为抽运源, 增益光纤芯径20μm, 长度2.4m。在种子光功率40mW、一级放大的抽运功率6.8W、二级放大的抽运功率85W时, 得到了42W的1064nm信号光输出。结果表明, 光光转换效率约49.4%, 偏振消光比27.5dB; 输出信号光中心波长1064.5nm, 线宽约70MHz, 保持了种子光的单频特性。在42W连续输出时没有观察到受激布里渊散射, 继续增大抽运功率, 有望实现更高功率的放大。

In order to suppress the stimulated Brillouin scattering effect and increase the amplification power of single frequency narrow linewidth seed source, master oscillator power amplifier (MOPA) structure was adopted. Fiber length, core diameter and pumping parameters were optimized. Optical output of 42W signal at 1064nm was realized. In the experiment, the first stage amplification used 914nm semiconductor laser as pumping source with gain fiber core diameter of 10μm and length of 8m. The second stage amplifier used 976nm semiconductor laser as the pumping source with gain fiber core diameter of 20μm and length of 2.4m. When seed power is 40mW, pump power of the first stage amplification is 6.8W and pump power of the second stage amplification is 85W, optical output 42W of the signal at 1064nm was obtained. The results show that light-to-light conversion efficiency is about 49.4%, polarization extinction ratio is 27.5dB; central wavelength of output signal light is 1064.5nm, and linewidth is about 70MHz. Single-frequency characteristics of seed light are maintained. Stimulated Brillouin scattering is not observed at 42W continuous output. Continuous increase of pump power is expected to achieve higher power amplification.