Modal Analysis of Fiber Laser Beam by Using Stochastic Parallel Gradient Descent Algorithm

The ability of modal decomposition based on the analysis of the near-field intensity profile using the stochastic parallel gradient descent algorithm is experimentally characterized in detail for the first time. The results show that the decomposition method proposed in this letter turns to be highly accurate and rapid. Further, this method is applied to analyze the mode behavior in dependence on the pump power in a high-power fiber amplifier with different initial mode compositions.