Experimental demonstration of transverse mode instability enhancement by a counter-pumped scheme in a 2  kW all-fiberized laser

Li, Zebiao; Huang, Zhihua; Xiang, Xiaoyu; Liang, Xiaobao; Lin, Hungyen; Xu, Shanhui; Yang, Zhongmin; Wang, Jianjun; Feng, Jing

doi:10.1364/prj.5.000077

Cited by 57 publications

(20 citation statements)

References 13 publications

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“…The TMI threshold, nonlinear threshold and total thermal loads at the TMI thresholds of the considered fibres are provided in Table 4.9. According to our calculation, the commercial LMA fibre (type 1) has a TMI threshold power at 2080 W when the PD is absent, which is close to the experimental result of 1900 W in [125]. Under the presence of PD, TMI threshold is at 920 W. This considerably high TMI threshold is attributed to the large CCAR of fibre, which makes the pump saturation effect strong.…”

Section: Transverse Mode Instability Suppression In the Presence Of Pdsupporting

confidence: 83%

“…Based on the parametric studies in previous sections, this section examines improved fibre design for TMI suppression when PD is unavoidable. We adopt commercial LMA fibre parameters for a PD fibre [125] and the parameters from [73] for a PD resistant fibre, for comparison with our improved TMI-suppressed PD fibre. The TMI-suppressed PD fibre design uses the following strategies: I first reduce the ion concentration to suppress the PD-induced loss and thermal load, which results in a longer fibre to keep the same pump absorption.…”

Section: Transverse Mode Instability Suppression In the Presence Of Pdmentioning

confidence: 99%

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Investigation of transverse mode instability suppression in large mode area fibre

Xia¹

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In the past decades, fibre laser and amplifier systems have seen a rapid power increase due to the efficient heat dissipation and robust single-mode operation. The fibre lasers and amplifiers have become attractive sources for applications spanning from industry and defence to scientific research. In particular, the fibre lasers and amplifiers have penetrated for material processing industry including marking, cutting, welding and drilling. It had been known that the highest achievable output power in fibre laser and amplifier systems is largely limited by the nonlinear scatterings such as stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). However, a new phenomenon under high power operation, the so-called transverse mode instability (TMI), was experimentally observed in a large mode area (LMA) ytterbium (Yb)-doped fibre amplifier in 2011. The TMI can occur much earlier than the SBS and SRS in average power scaling, hence becoming the first limitation in high-power fibre operations till now. The TMI refers to the output beam degradation, caused by the power transfer from the fundamental mode (FM) to the higher-order mode (HOM), for input pump power above a certain threshold. The origin of TMI is attributed to the stimulated thermal Rayleigh scattering x

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Section: Transverse Mode Instability Suppression In the Presence Of Pdsupporting

confidence: 83%

Section: Transverse Mode Instability Suppression In the Presence Of Pdmentioning

confidence: 99%

Investigation of transverse mode instability suppression in large mode area fibre

Xia¹

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“…Comparing to co-pumped amplifier, stimulated Raman scattering and four-wave mixing can be suppressed in the counter-pumped scheme [20]. We guess that the SBS can also be suppressed with counter-pumped scheme.…”

Section: Introductionmentioning

confidence: 84%

Spectral evolution and stimulated Brillouin scattering suppression in phase-modulated fiber amplifier

et al. 2018

Self Cite

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The model combining power balance equations, coupling amplitude equations and stimulated Brillouin scattering (SBS) equation is established to simulate the spectrum evolution and SBS threshold in the amplifier stage. Four typical phase modulation seeds are employed to calculate the SBS spectrum evolution in fiber amplifier. The spectrum evolution results show that the top-hat shaped spectrum seed is optimal to suppress the SBS effect and scale the SBS threshold. The SBS threshold is studied in co-pumped and counter-pumped amplifiers. Simulation results show that counter-pumped amplifier is capable of generating about 2.5 times more output than co-pumped amplifier. The results provide theoretical basis on the design and experiment of continuous wave high power narrow linewidth fiber laser.

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“…Very recently, a new type of mode degradation phenomenon named mode distortion induced by stimulated Raman scattering (SRS) was proposed [31,32] , but mode distortion and the SRS effect were considered as independent phenomena previously. The SRS-induced mode distortion occurs suddenly and the beam quality deteriorates at the same time once the output power of fiber laser exceeds a certain value (several hundred to several thousand watts), which exhibits obvious threshold behaviors [33] .…”

Section: Introductionmentioning

confidence: 99%

Effective suppression of mode distortion induced by stimulated Raman scattering in high-power fiber amplifiers

Gao

Fan

et al. 2021

High Pow Laser Sci Eng

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Mode distortion induced by stimulated Raman scattering (SRS) has become a new obstacle for the further development of high-power fiber lasers with high beam quality. Here, an approach for effective suppression of the SRS-induced mode distortion in high-power fiber amplifiers has been demonstrated experimentally by adjusting the seed power (output power of seed source) and forward feedback coefficient of the rear port in the seed source. It is shown that the threshold power of the SRS-induced mode distortion can be increased significantly by reducing the seed power or the forward feedback coefficient. Moreover, it has also been found that the threshold power is extremely sensitive to the forward feedback power value from the rear port. The influence of the seed power on the threshold power can be attributed to the fact that the seed power plays an important role in the effective length of the gain fiber in the amplifier. The influence of the forward feedback coefficient on the threshold power can be attributed to the enhanced SRS configuration because the end surface of the rear port together with the fiber in the amplifier constitutes a half-opening cavity. This suppression approach will be very helpful to further develop the high-power fiber amplifiers with high beam quality.

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Experimental demonstration of transverse mode instability enhancement by a counter-pumped scheme in a 2 kW all-fiberized laser

Cited by 57 publications

References 13 publications

Investigation of transverse mode instability suppression in large mode area fibre

Investigation of transverse mode instability suppression in large mode area fibre

Spectral evolution and stimulated Brillouin scattering suppression in phase-modulated fiber amplifier

Effective suppression of mode distortion induced by stimulated Raman scattering in high-power fiber amplifiers

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