SRS modeling in high power CW fiber lasers for component optimization

Brochu, Guillaume; Villeneuve, A.; Faucher, Mathieu; Morin, Michel; Trepanier, Francois; Dionne, R.

doi:10.1117/12.2248336

Cited by 12 publications

(4 citation statements)

References 14 publications

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“…On the other hand, though the configuration of our system is approximate to that of [26], the bandwidths of the OC FBG in the oscillators are different-0.15 nm and 0.4 nm respectively. Previous works have demonstrated that the oscillator induces stronger temporal fluctuations when using a narrower OC FBG, and the SRS effect and spectral broadening increase quickly with enhanced temporal fluctuations [27][28][29][30][31]. This may explain why the SRS and spectral broadening in our amplifier are more remarkable.…”

Section: Srs Effect With Different Types Of Seed Laser Injectionmentioning

confidence: 62%

3.5 kW bidirectionally pumped narrow-linewidth fiber amplifier seeded by white-noise-source phase-modulated laser

Zha

Sun

et al. 2018

Laser Phys.

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We demonstrate an all-fiber narrow-linewidth amplifier employing a bidirectional pump scheme and cascaded white-noise-source phase-modulated seed laser. The stimulated Raman scattering effect in the amplifier is investigated by substituting different types of seed lasers. The influence of pump distributions and seed injection power on mode instability (MI) in the amplifier is also experimentally investigated. As a result, a 3 dB linewidth of 0.175 nm and a beam quality of M 2 ≈ 1.5 are obtained at the output of ~3 kW, without observation of MI and stimulated Brillouin scattering effect. With the further increase of pump power, MI occurs as the output exceeds 3.17 kW, along with beam quality degradation. Optical efficiency decreases to 71.5% at the ultimate output of 3.5 kW. Therefore MI becomes the main limitation to further power scaling.

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Section: Srs Effect With Different Types Of Seed Laser Injectionmentioning

confidence: 62%

3.5 kW bidirectionally pumped narrow-linewidth fiber amplifier seeded by white-noise-source phase-modulated laser

Zha

Sun

et al. 2018

Laser Phys.

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“…The FBGs are inscribed on the double cladding fiber with a core/inner cladding diameter of 25/400 µm utilizing the phase mask method in the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science. According to recent studies [35][36][37], FBG bandwidths have a notable influence on the Raman threshold of the monolithic fiber laser oscillator, and a pair of broadband FBGs can help to enhance the Raman threshold. Therefore, the home-made FBGs are designed as broadband FBGs.…”

Section: Methodsmentioning

confidence: 99%

Monolithic fiber laser oscillator with record high power

et al. 2018

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With an increasing output power, the power scaling of monolithic fiber laser oscillators faces the severe limitations of stimulated Raman scattering (SRS) and the transverse mode instability (TMI) effect. In this work, we report a high power monolithic fiber laser oscillator with a maximum output power of 5.2 kW, which is realized with a trade-off design between the SRS and TMI. The monolithic fiber laser oscillator is constructed with ytterbium-doped fiber with a core/inner cladding diameter of 25/400 µm and corresponding home-made FBG. High-power 915 nm laser diodes are employed as a pump source and are distributed in a bidirectional-pump configuration. By optimizing the bidirectional pump proportion, the monolithic fiber laser oscillator is scaled up to 5.2 kW with a slope efficiency of ~63%. Operating at 5.2 kW, the intensity of the Raman stokes light is ~22 dB below the signal laser and the beam quality (M2-factor) is ~2.2. To the best of our knowledge, this is a record high power for monolithic fiber laser oscillators.

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“…In previous works, some theoretical and experimental studies showed the limitations of the SRS effect can be mitigated by decreasing the active fiber length [21], enlarging the fiber mode area [22] or broadening the bandwidth of FBGs [23]. However, the experimental studies on the bandwidth of FBGs for the SRS effect were mainly concentrated in the cases of fiber oscillators with space-coupled configuration or all-fiber laser oscillators with low average power gain.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of SRS threshold dependence on the bandwidths of fiber Bragg gratings in co-pumped and counter-pumped fiber laser oscillator

Yang

Wang

et al. 2019

J. Opt.

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With increasing output power, stimulated Raman scattering (SRS) becomes one of the main limitations for high power fiber laser oscillators. In this work, the SRS threshold dependence on the bandwidths of fiber Bragg gratings (FBGs) has been experimentally investigated in co-pumped and counter-pumped ytterbium-doped all-fiber laser oscillators, respectively. In both co-pumped and counter-pumped laser oscillators, FBGs with respective bandwidths of 0.24 nm, 0.5 nm, 1 nm and 2 nm are used as the output coupler. It is found that with the increasing bandwidth of the output-coupler FBG (OC-FBG), the SRS threshold of the laser oscillator also increases and when the bandwidth of the OC-FBG reaches over ∼1 nm, the SRS threshold increases slowly. Compared with co-pumping configuration, a counter-pumped laser oscillator holds a higher SRS threshold when the same OC-FBG is applied. By employing a counter-pumping configuration and increasing the bandwidth of the OC-FBG to 2 nm, the output laser power is further scaled to 3 kW-level with a slope efficiency of 70%. The M2 factor is measured to be ∼1.3 at the maximum output power.

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SRS modeling in high power CW fiber lasers for component optimization

Cited by 12 publications

References 14 publications

3.5 kW bidirectionally pumped narrow-linewidth fiber amplifier seeded by white-noise-source phase-modulated laser

3.5 kW bidirectionally pumped narrow-linewidth fiber amplifier seeded by white-noise-source phase-modulated laser

Monolithic fiber laser oscillator with record high power

Experimental study of SRS threshold dependence on the bandwidths of fiber Bragg gratings in co-pumped and counter-pumped fiber laser oscillator

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