C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, "Phase-shift evolution between the modal interference pattern and the thermally-induced refractive index grating in high-power fiber laser systems," Opt. Express 26, 19489–19497 (2018).
A phase shift between the modal interference pattern and the thermally-induced refractive index grating is most likely the ultimate trigger for the damaging effect of transverse mode instabilities (TMI) in high-power fiber laser systems. By using comprehensive simulations, the creation and evolution of a thermally-induced phase shift is explained and illustrated in detail. It is shown that such a phase shift can be induced by a variation of the pump power. The gained knowledge about the generation and evolution of the phase shift will allow for the development of new mitigation strategies for TMI.