Intensity noise as a driver for transverse mode instability in fiber amplifiers

Christoph Stihler; Cesar Jauregui; Sobhy E. Kholaif; Jens Limpert

doi:10.1186/s43074-020-00008-8

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Christoph Stihler, Cesar Jauregui, Sobhy E. Kholaif, Jens Limpert. Intensity noise as a driver for transverse mode instability in fiber amplifiers[J]. PhotoniX. doi: 10.1186/s43074-020-00008-8

Citation:

Christoph Stihler, Cesar Jauregui, Sobhy E. Kholaif, Jens Limpert. Intensity noise as a driver for transverse mode instability in fiber amplifiers[J]. PhotoniX. doi: 10.1186/s43074-020-00008-8

Christoph Stihler, Cesar Jauregui, Sobhy E. Kholaif, Jens Limpert. Intensity noise as a driver for transverse mode instability in fiber amplifiers[J]. PhotoniX. doi: 10.1186/s43074-020-00008-8

Citation:

Christoph Stihler, Cesar Jauregui, Sobhy E. Kholaif, Jens Limpert. Intensity noise as a driver for transverse mode instability in fiber amplifiers[J]. PhotoniX. doi: 10.1186/s43074-020-00008-8

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Intensity noise as a driver for transverse mode instability in fiber amplifiers

doi: 10.1186/s43074-020-00008-8

1.
Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Albert-Einstein-Str
2.
Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Str
3.
Helmholtz-Institute Jena, Fröbelstieg 3, 07743, Jena, Germany

Funds:

Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)-416342637

416342891

GRK 2101 (259607349). Fraunhofer Gesellschaft-Fraunhofer Cluster of Excellence "Advanced Photon Sources".

Received Date: 2019-11-29
Accepted Date: 2020-02-10

Available Online: 2020-03-10

Abstract

Abstract

The effect of transverse mode instability (TMI) is currently the main limitation for the further average-power scaling of fiber laser systems with diffraction-limited beam quality. In this work a main driving force for TMI in fiber amplifiers is identified. Our experiments and simulations illustrate that the performance of fiber laser systems in terms of their diffraction-limited output power can be significantly reduced when the pump or seed radiation exhibit intensity noise. This finding emphasizes the fact that the TMI threshold is not only determined by the active fiber but, rather, by the whole system. In the experiment an artificially applied pump intensity-noise of 2.9% led to a reduction of the TMI threshold of 63%, whereas a similar seed intensity-noise decreased it by just 13%. Thus, even though both noise sources have an impact on the TMI threshold, the pump intensity-noise can be considered as the main driver for TMI in saturated fiber amplifiers. Additionally, the work unveils that the physical origin of this behavior is linked to the noise transfer function in saturated fiber amplifiers. With the gained knowledge and the experimental and theoretical results, it can be concluded that a suppression of pump-noise frequencies below 20 kHz could strongly increase the TMI threshold in high-power fiber laser systems.
- Transverse mode instability,
- Fiber lasers,
- Thermal effects,
- Intensity noise,
- Modal interference,
- Refractive index grating,
- Mode coupling,
- Phase shift

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References(26)

References

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