Analysis of factors affecting transverse mode instability in high-power thulium-doped fiber lasers

Abstract

Transverse Mode Instability (TMI) effect has become the biggest obstacle limiting the further improvement of output power and beam quality in high-power fiber lasers. For 2μm-band high-power thulium-doped fiber laser, the simulation is carried out using semi-analytical theoretical model. The results show that the TMI threshold is negatively correlated with the core radius, signal wavelength and positively correlated with the pump wavelength. On the other hand, reducing the relative intensity noise can slightly but not obviously improve the TMI threshold. The relationship curve between them is nearly logarithmic. The simulation provides an effective reference for further improving the TMI threshold.