Abstract

Power scaling of fiber lasers is hindered by nonlinear and thermal limitations. The most dramatic limiting effect is transverse mode instability (TMI). It manifests as fluctuations between the fundamental mode (FM) of the fiber and a high order mode (HOM). So far there has not been much research of TMI in polarization maintaining (PM) fibers. Simulations in [1] predicted that different input polarization angles can lead to suppression of TMI. Experimentally, it was reported in [2] that rotating the fiber at the splicing point of a PM fiber led to changes on the TMI threshold. Here in this work, we present systematic measurements of the TMI threshold in a PM large mode area (LMA) fiber in dependence on the input linear polarization angle. We demonstrate that TMI can be strongly influenced by detuning the linear polarization of the seed with respect to the slow-axis of the fiber.

© 2023 IEEE