M<sup>2</sup> factor estimation in few-mode fibers based on a shallow neural network
Min Jiang, Yi An, Liangjin Huang, Jun Li, Jinyong Leng, Rongtao Su, Pu Zhou
Abstract
A high-accuracy, high-speed, and low-cost M 2 factor estimation method for few-mode fibers based on a shallow neural network is presented in this work. Benefiting from the dimensionality reduction technique, which transforms the two-dimension near-field image into a one-dimension vector, a neural network with only two hidden layers can estimate the M 2 factor directly. In the simulation, the mean estimation error is smaller than 3% even when the mode number increases to 10. The estimation time of 10000 simulation test samples is around 0.16s, which indicates a high potential for real-time applications. The experiment results of 50 samples from the 3-mode fiber have a mean estimation error of 0.86%. The strategies involved in this method can be easily extended to other applications related to laser characterization.