Modeling of CW Yb-doped fiber lasers with highly nonlinear cavity dynamics

S K Turitsyn,M P Fedoruk,A A Fotiadi,A E Bednyakova,E Sholokhov,A S Kurkov,A I Latkin

doi:10.1364/oe.19.008394

Abstract

We develop a theoretical framework for modeling of continuous wave Yb-doped fiber lasers with highly nonlinear cavity dynamics. The developed approach has shown good agreement between theoretical predictions and experimental results for particular scheme of Yb-doped laser with large spectral broadening during single round trip. The model is capable to accurately describe main features of the experimentally measured laser outputs such as power efficiency slope, power leakage through fibre Bragg gratings, spectral broadening and spectral shape of generated radiation.

Highlights

Modeling of continuous wave (CW) lasers is traditionally considered to be somewhat less complicated compared to analysis of pulsed lasers
Averaged models dealing with an average optical power and neglecting the phase of optical field and time dynamics of the radiation are commonly used for analysis of CW fiber lasers
At right side of the cavity fiber Bragg grating (FBG) cuts the central part of the radiation spectrum which experiences nonlinear phase shift due to Kerr effect and leaves the cavity through the flat end

Summary

Introduction

Modeling of continuous wave (CW) lasers is traditionally considered to be somewhat less complicated compared to analysis of pulsed lasers (see e.g [1]. and references therein). Many modern high-power, the so-called CW lasers, generate radiation output that only on average can be treated as a constant power wave, and as a matter of fact, is rather a pulsating irregular field. When deviations of such pulsations from an average level are not small and they do not have impact on the device performance, temporal dynamics of the radiation can be neglected and power average models can be used for description of performance of such laser systems. Temporally modulated radiation propagating along the fibre cavity at high powers can be spectrally broadened due to nonlinear Kerr effect. An accurate modeling of spectral broadening in the context of high-power CW lasers is a challenging numerical problem and in this work we propose and examine a simplified numerical approach to this problem

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Conclusion