Power scaling limits of diffraction-limited fiber amplifiers considering transverse mode instability

Abstract

An empirical TMI threshold formula is derived based on a recently developed model and used to analyze the power-scaling performance of ytterbium-doped silica glass and YAG (Y 3 Al 5 O 12 ) and lutetia (Lu 2 O 3 ) single-crystalline fiber amplifiers. Overall, the single-crystalline fiber lasers are found to scale potentially to higher average powers due to their higher thermal conductivities compared to silica glass. This work serves as a useful extension to earlier works and shines significant new light on optimal fiber and amplifier designs for maximum average output power with TMI considered.