Influence of mode distortion on the transverse mode competition in large-mode-area amplifiers

In large mode area fiber amplifier, it is difficult to avoid the bend induced mode distortion. With the existence of mode distortion taken into account, a previous transverse mode competition model has been improved. Based on this model and the finite element difference-beam propagation method, the behaviors of bent mode competition are demonstrated and compared with the straight mode competition where the mode distortion is neglected, the comparison and quantitative results show that serious mode distortion can change the appearance of transverse mode competition in bent fiber amplifiers and even drastically degrade the amplifier performance.