title: Thermally induced mode coupling in rare-earth doped fiber amplifiers.
abstract: We present a simple semianalytical model of thermally induced mode coupling in multimode rare-earth doped fiber amplifiers. The model predicts that power can be transferred from the fundamental mode to a higher-order mode when the operating power exceeds a certain threshold, and thus provides an explanation of recently reported mode instability in such fiber amplifiers under high average-power operation. We apply our model to a simple step-index fiber design, and investigate how the power threshold depends on various design parameters of the fiber.
authors: Department of Photonics Engineering, Technical University of Denmark Bldg. 345A, DK-2800 Kgs. Lyngby, Denmark. kryh@fotonik.dtu.dk
authors: Kristian Rymann
authors: KR
authors: Hansen
authors: Thomas Tanggaard
authors: TT
authors: Alkeskjold
authors: Jes
authors: J
authors: Broeng
authors: Jesper
authors: J
authors: Lægsgaard