多芯光纤激光器增益场选模效应研究

对多芯光纤激光器的增益场选模效应进行了初步研究。利用矢量耦合模理论计算多芯光纤激光器支持的各类超模的模式特性,并对其增益系数进行计算,比较不同功率等级下各超模增益特性的异同。计算结果表明,在较低功率下。多芯光纤激光器各类超模增益系数大小基本一致,输出光束是由各超模组成的混合模式; 而当激光功率较高时,同相模的增益系数大小明显大于其它模式,在模式竞争中占据优势,激光器输出光束远场具备同相模的特征。最后对多芯光纤激光器增益场选模效应的适用范围进行了简单讨论。

Study on Mode Filtering by Gain Structure in Multicore Fiber Lasers

Mode filtering by gain structure in multicore fiber laser is studied. The supermode distribution of a 7-core fiber laser is calculated by the vector coupled-mode theory, and gain coefficients for different supermodes in different power-levels are calculated. It is shown that in a low power level, gain coefficients for different supermodes almost equal to each other, the far-field laser profile emitted from the multicore fiber laser will give mix-mode character. When the laser output power is in a higher level, the gain coefficient for the in-phase mode is the largest among all the supermodes, which will dominate the mode competition. The far-field laser profile will show in-phase mode character. The validity for the mode filtering by gain structure is discussed.