Accurate and efficient modeling of the transverse mode instability in high-energy laser amplifiers using the phase-matched model

Abstract

We review recent work in which we developed a phase-matched model to study the transverse mode instability (TMI) in high-energy laser amplifiers. The standard models for TMI have contributions that vary rapidly compared to the beat period between the fundamental mode and the higher-order modes in the problem. In the phase-matched model, we neglect these rapidly varying contributions. We consider a realistic example with a Yb-doped fiber amplifier that is similar to the amplifier that was considered by Naderi et al. [Opt. Exp., 21(13), 16111 (2013)], but with a more realistic 10-m length. In this example, only one higher-order mode is present. We show that the computational speedup of the phase-matched model is on the order of 100 with no loss of accuracy even in the highly-saturated nonlinear regime.