High-speed modal analysis of dynamic modal coupling in fiber laser oscillator

Up till now, the spatial and temporal dynamics of transverse mode instability (TMI) in fiber laser oscillator have increasingly attracted a worldwide attention. Here, we develop high-speed modal decomposition (MD) system to analyze coupling for above TMI threshold. A set angular-multiplexing transmission functions (TFs) are designed simultaneous MD monitoring far-field beam profile. The threshold deployed is 181 W at co-pumping power (CPP) 279 W. As CPP increases from 318 397 W, fluctuations output become more drastic. changes profile centroid spot (COFFS) indicate an increased velocity energy transfer between modes. verifies process analyzes components, indicating that single cycle decreases 11 ms 4 ms. Otherwise, strong occurs modes with relatively large weights. provides powerful tool research effect.