Steady-periodic method for modeling mode instability in fiber amplifiers

TL;DR

This paper introduces a steady-periodic modeling approach for mode instability in high-power fiber amplifiers, enabling efficient analysis of steady-state behavior and adaptable to transient conditions.

Contribution

It presents a novel steady-periodic method combining Fourier-based propagation, steady gain solutions, and heat equation solvers for fiber amplifier mode instability modeling.

Findings

Efficient steady-state modeling of mode instability.

Adaptability to transient conditions.

Integration of Fourier transforms and heat equation solutions.

Abstract

We present a detailed description of the methods used in our model of mode instability in high-power, rare earth-doped, large-mode-area fiber amplifiers. Our model assumes steady-periodic behavior, so it is appropriate to operation after turn on transients have dissipated. It can be adapted to transient cases as well. We describe our algorithm, which includes propagation of the signal field by fast-Fourier transforms, steady-state solutions of the laser gain equations, and two methods of solving the time-dependent heat equation: alternating-direction-implicit integration, and the Green's function method for steady-periodic heating.