2×2全光纤激光器阵列部分相干合成的实验研究

Experimental study on partially coherent combination of a 2×2 all-fiber laser array

对2×2全光纤激光器阵列的部分相干合成进行了实验研究。将四台全光纤激光器阵列分为两组,组内两光纤激光器通过一个对激光波长具有一定反射率的光纤光栅实现腔模互注入相位锁定,而两组激光阵列元之间非相干。四束激光经一个四面直角棱镜反射后尽量接近并实现对称排布。获得两组清晰的干涉条纹,条纹最大可见度分别约为43%和38%。整个激光器阵列在泵浦光总功率为1624W时获得925W高功率部分相干输出。在合成光束占空比为0.54时,合成光束的光束质量BQ值约为1.95。激光器阵列由全光纤元件组成,系统结构紧凑,在长时间的高功率合成实验中,性能稳定,没有观察到光热损伤现象。

By using partially coherent combining technique,beam combining of a 2×2 all-fiber laser array was experimentally studied.The laser array consisted of two incoherent laser groups.Each group contained two all-fiber lasers which were phase-locked by using direct mode mutual injection method through a fiber Bragg grating with proper reflectivity.The four laser beams were arranged symmetrically.And they were placed as close as possible by using a four-right-angle prism.In the experiment,two groups of clear interfere strips with maximum visibility of about 43% and 38% were observed,respectively.The whole laser array finally generates 925 W output power when the total pump power was 1 624 W.The beam-quality value BQ of the combined beam emitting from the laser array was 1.95 when the fill factor of the laser array was 0.54.This fiber laser combining array was constructed by all-fiber components,thereby was monolithic with stable performance.During the long time of high power operation,the monolithic fiber laser array works with excellent stability,no thermal distortion and damage are observed.