Beam mode analysis of non-PM narrow linewidth fiber amplifier by polarization control states

We studied beam mode analysis of non-PM narrow linewidth fiber amplifier by polarization change using LiNbO3 polarization controller. According to polarization control status, we analyzed that M2 and DOLP are related on LP mode distribution using SPGD based modal decomposition. Beam mode analysis by SPGD based modal decomposition will be expected to use for the polarization control algorithm tuning and beam pattern analysis of narrow linewidth fiber laser.