Modal instabilities in high power fiber laser oscillators

Transverse mode competition and instabilities in high-power fiber oscillators have been studied experimentally by monitoring the dynamic power exchanges and characteristic frequencies of the transmitted fundamental mode (FM) and scattered high-order modes (HOMs) of the fiber laser cavity under CW an...

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Bibliographic Details
Published in:Optics express 2019-02, Vol.27 (4), p.4386-4403
Main Authors: Scarnera, V, Ghiringhelli, F, Malinowski, A, Codemard, C A, Durkin, M K, Zervas, M N
Format: Article
Language:English
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Summary:Transverse mode competition and instabilities in high-power fiber oscillators have been studied experimentally by monitoring the dynamic power exchanges and characteristic frequencies of the transmitted fundamental mode (FM) and scattered high-order modes (HOMs) of the fiber laser cavity under CW and pulsed pumping. The FM and HOM power evolution indicates the presence of two competing effective laser cavities which result in rich output dynamics and full chaotic operation. The thermal and inversion related contributions to the observed instabilities have been identified by monitoring the associated characteristic instability frequencies under pulsed pumping. It is shown that in the transient regime, both inversion and thermal effects contribute successively to the observed power instabilities. Increasing the pump power leads to full chaotic response through an interplay between transverse and longitudinal mode instabilities.
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.27.004386