Static modal energy transfer in high power, polarization maintaining fiber laser systems
In this work, we predict the existence of static modal energy transfer in polarization-maintaining (PM) fibers. This phenomenon, related to the effect of transverse mode instability (TMI), appears because of the coexistence of two modal interference patterns and two thermally induced index gratings (one of each per polarization axis in the fiber) with slightly different periods. This static energy transfer can be exploited to create an early warning system for TMI in PM fibers. Moreover, this technique can become an invaluable tool to gain further insights into the physics of TMI.