Theory and modeling of photodarkening-induced quasi static degradation in fiber amplifiers

Ward, Benjamin G.

doi:10.1364/oe.24.003488

Cited by 46 publications

(29 citation statements)

References 22 publications

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“…It is well known that LMA fibers can suffer from transverse modal instability (TMI) or photodarkening induced modal degradation. TMI has been extensively studied [31], but photodarkening induced modal degradation has been identified more recently [32][33][34]. This phenomenon leads to a power roll-over combined with an increase of cladding light during photodarkening process.…”

Section: Modal Stability and Photodarkening Investigationmentioning

confidence: 99%

Ultra-low intensity noise, all fiber 365 W linearly polarized single frequency laser at 1064 nm

Dixneuf¹,

Guiraud²,

Bardin³

et al. 2020

Opt. Express

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We demonstrate a robust linearly polarized 365 W, very low amplitude noise, single frequency master oscillator power amplifier at 1064 nm. Power scaling was done through a custom large mode area fiber with a mode field diameter of 30 µm. No evidence of stimulated Brillouin scattering or modal instabilities are observed. The relative intensity noise is reduced down to −160 dBc/Hz between 2 kHz and 10 kHz via a wide band servo loop (1 MHz bandwidth). We achieve 350 W of isolated power, with a power stability < 0.7% RMS over 1100 hours of continuous operation and a near diffraction limited beam (M 2 < 1.1).

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Section: Modal Stability and Photodarkening Investigationmentioning

confidence: 99%

Ultra-low intensity noise, all fiber 365 W linearly polarized single frequency laser at 1064 nm

Dixneuf¹,

Guiraud²,

Bardin³

et al. 2020

Opt. Express

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“…A maximum signal output power of 118 W is achieved at a pump power of 173 W. The main obstacle involved with power scaling is fiber modal degradation produced by power transfer from the fundamental mode to higher order modes. This process is caused by a photo-darkening-induced thermo-optic index grating which leads to mode instability [20,21]. The measured mode instability threshold is >120 W. Above such power, the laser output degrades into higher-order modes after long-term operation (a few hours).…”

Section: W Fiber Amplifier Output Characterizationmentioning

confidence: 99%

High-power all-fiber ultra-low noise laser

et al. 2018

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High-power ultra-low noise single-mode single-frequency lasers are in great demand for interferometric metrology. Robust, compact all-fiber lasers represent one of the most promising technologies to replace the current laser sources in use based on injection-locked ring resonators or multi-stage solid-state amplifiers. Here, a linearly-polarized high-power ultra-low noise allfiber laser is demonstrated at a power level of 100 W. Special care has been taken in the study of relative intensity noise (RIN) and its reduction. Using an optimized servo actuator to directly control the driving current of the pump laser diode (LD), we obtain a large feedback bandwidth of up to 1.3 MHz. The RIN reaches -160 dBc/Hz between 3 kHz and 20 kHz.

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“…However, it has not been thoroughly investigated the relationship of heating, PD, saturation effect and TMI simultaneously. [70,[72][73][74]. In particular, an average heat load was suggested as an alternative quantity for TMI threshold [75].…”

Section: Motivationmentioning

confidence: 99%

“…The TMI behaviours in high-power fibre operation can be modelled via the numerical [76][77][78][79][80], analytical or semi-analytical models [81][82][83][84][85][86][87]. The numeric models presented in [77,79] [88].…”

Section: Chapter 2 Theoretical Model Of the Transverse Mode Instabilitymentioning

confidence: 99%

“…Recently, the PD-induced heat from absorption of both signal and pump is recognized as another heat source contributing to the TMI [75,80]. The TMI behaviours at the presence of PD has been experimentally investigated in [75] as well as theoretically studied in [74,75,85]. However, the prior theoretical investigations were somewhat limited to portray the various interactive effects on TMI such as pump saturation, thermal lensing, and mode coupling effects.…”

Section: Chapter 4 Power Scaling In Photodarkening Fibre By Transversmentioning

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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Theory and modeling of photodarkening-induced quasi static degradation in fiber amplifiers

Cited by 46 publications

References 22 publications

Ultra-low intensity noise, all fiber 365 W linearly polarized single frequency laser at 1064 nm

Ultra-low intensity noise, all fiber 365 W linearly polarized single frequency laser at 1064 nm

High-power all-fiber ultra-low noise laser

Investigation of transverse mode instability suppression in large mode area fibre

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