Wavelength stabilized multi-kW diode laser systems

Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, P.; Hubrich, Ralf; Beczkowiak, A.; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

doi:10.1117/12.2079428

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…In the following decade, several research groups and companies studied wavelength stabilization by use of reflective VBGs in external cavities [8][9][10][11]. Since then, up to 3.4 kW optical power have been demonstrated from a single stack [12] and fiber coupled pump sources are available off the shelve with optical powers above 200 W [13]. However, insufficient feed-back into the waveguide can lead to side lobes in the spectrum that significantly reduce the power content in the desired wavelength interval (typically 1 nm) [14,15].…”

Section: Wavelength Stabilizationmentioning

confidence: 99%

Wavelength stabilization and feedback sensitivity of multi-kW diode laser stacks

Witte,

Dommermuth,

Weber

et al. 2024

High-Power Diode Laser Technology XXII

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In the first part of this paper, we report on a fiber-coupled wavelength-stabilized high power diode laser system with an optical output power of more than 4 kW at a wavelength of 969 nm. The spectrum is locked over the entire working range with a FWHM of less than 0.5 nm. More than 90% power is encircled within 0.7 nm. The radiation is coupled into a fiber with a core diameter of 1000 µm. Additionally, we show the way for further power scaling up to 8 kW by using diode laser bars that enable higher injection current and output power. In the second part of this paper, we report on the impact of external back-reflections on the diode laser either by long term operation with VBGs or by short term operation in an experimental set-up based on a partially reflective mirror. For our standard set-up with VBG, we do not observe any feedback induced failures or degradation for operating times up to 3,000 hours. However, as expected, we do observe failures with increased feedback. In accordance with the literature, misalignment towards the p-clad can be very critical at wavelengths greater than 960 nm. The feedback-induced failure-rate increases exponentially with the injection current which make high power diode laser bars with high filling factors a very robust solution for external wavelength stabilization.

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Section: Wavelength Stabilizationmentioning

confidence: 99%

Wavelength stabilization and feedback sensitivity of multi-kW diode laser stacks

Witte,

Dommermuth,

Weber

et al. 2024

High-Power Diode Laser Technology XXII

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Analytical model of a diode-pumped cesium laser for investigation of upper-state mixing and quenching reactions

Endo¹,

Nagaoka²,

Wani³

2023

Opt. Express

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A one-dimensional analytical model of a diode-pumped cesium vapor laser was constructed, and equations were derived to explain the dependence of the laser power on the hydrocarbon gas partial pressure. By varying the hydrocarbon gas partial pressure over a wide range and measuring the laser power, the corresponding mixing and quenching rate constants were validated. A gas-flow Cs diode-pumped alkali laser (DPAL) was operated with methane, ethane, and propane as buffer gases, with the partial pressures varied from 0 to 2 atmospheres. The experimental results were found to be in good agreement with the analytical solutions, confirming the validity of our proposed method. Separate 3-D numerical simulations were performed, and the output power effectively reproduced the experimental results over the entire buffer gas pressure range.

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Wavelength stabilization of high-power laser diodes using Bragg gratings inscribed in their highly multimode fiber pigtails

et al. 2022

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Efficient wavelength stabilization of an off-the-shelf high-power laser diode operating at 976 nm is demonstrated by using a highly multimode fiber Bragg grating (FBG). This first-order grating is inscribed with 400 nm femtosecond pulses inside the 200 µm/0.22 NA pure silica core of the diode’s fiber pigtail. The FBG reduces the wavelength thermal drift of the 70 W diode by a factor of 12 while also reducing its emission linewidth by a factor of 2.8. At maximum output power, a power penalty of only 6% is measured. This promising approach offers a robust and compact scheme to stabilize the spectrum of high-power laser diodes that are particularly useful for fiber-laser pumping.

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Wavelength stabilized multi-kW diode laser systems

Cited by 3 publications

References 5 publications

Wavelength stabilization and feedback sensitivity of multi-kW diode laser stacks

Wavelength stabilization and feedback sensitivity of multi-kW diode laser stacks

Analytical model of a diode-pumped cesium laser for investigation of upper-state mixing and quenching reactions

Wavelength stabilization of high-power laser diodes using Bragg gratings inscribed in their highly multimode fiber pigtails

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