为获得高功率和高亮度光纤激光输出,设计了利用一块45°半透半反分束镜作为干涉元件,构建迈氏腔结构,使两路光纤激光器在输出端相干相长,从而实现相干合成输出的方案。从理论上分析了此方案的锁相机理,并在实验中成功实现了两路光纤激光器的相位锁定,使合成输出激光在自由空间传播,获得了功率约为360 mW的相干合成激光输出,功率合成效率约为73%,合成输出后的激光束在轴上光强获得了大幅度提高。本方案结构简单,利用了光纤耦合器干涉锁相的原理,但却避免了光纤耦合器承受功率低的缺点,所有元件均可承受高功率,因此可实现更高功率的相干合成激光输出,是一种有前途的高功率光纤激光器相干合成方案。

A phase-locking method for two individual fiber lasers is proposed to realize high power and high brightness fiber laser outputs.By taking a beam splitter with reflectivity of 50% at 45° as a interferomtric element to construct the Michelson cavity,two optical fiber lasers can realize coherent enhancement at output ends,so that the coherent combination output of two laser beams is complemented.The phase-locking principle is analyzed in detail and the phase-locking of two individual double clad fiber lasers is experimentally demonstrated.Experiments obtain a coherent combination laser output of 360 mW,and a power combination efficiency about 73%.Moreover,the on-axis power intensity is greatly enhanced.The phase-locking approach is simple and no power-limitation optical components,so the drawbacks of fiber couplers are eliminated and the output power can be further up scaled.These results show the method is one of the most promising phase-locking technologies in the high-power fiber laser coherent combination field.