Narrow linewidth, single mode 3 kW average power from a directly diode pumped ytterbium-doped low NA fiber amplifier

Beier, Franz; Hupel, Christian; Nold, Johannes; Kühn, Stefan; Hein, Sigrun; Ihring, J; Sattler, Bettina; Haarlammert, Nicoletta; Thomas, Sabu; Eberhardt, Ramona; Tünnermann, Andreas

doi:10.1364/oe.24.006011

Cited by 115 publications

(41 citation statements)

References 18 publications

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“…However, in the case of narrow linewidth operation (Δν < ~25GHz), the dependence of the TMI threshold on the core diameters appears to be much more severe (see Fig. 1; lower data setred dashed line), demonstrating that the seed linewidth has a strong effect on the TMI threshold [3]- [6].…”

Section:  mentioning

confidence: 98%

Transverse mode instability analysis in fiber amplifiers

Zervas

2017

SPIE Proceedings

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Mode instabilities in fiber amplifiers are analyzed by a new approach, considering the stability of the steady state FM amplification in the presence of transverse amplitude and/or phase perturbations, taking into account the effects of population inversion and thermal loading due to quantum-defect heating. Population inversion contribution to instability is shown to be dominant at low powers and high inversion. Under high powers and low inversion (high amplifier saturation) the thermal effects dominate the instability behavior. A simple and easy to interpret TMI power threshold formula is derived for the first time.

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Section:  mentioning

confidence: 98%

Transverse mode instability analysis in fiber amplifiers

Zervas

2017

SPIE Proceedings

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“…For a high-performance continuous-wave laser, singlemode operation is one of the fundamental requirements because it determines the coherence and power stability of the laser output 5,6,16 . For a long-cavity laser, for which it is preferable to have low phase noise, a narrow linewidth, and high optical power, single-mode lasing is challenging due to the small mode spacing 5,6,[16][17][18][19][20][21][22][23][24] . Since the gain spectrum of a gain medium in a laser cavity is usually several orders of magnitude broader than the mode spacing of the laser, the round-trip gain difference between adjacent modes is small, making it difficult to achieve single-mode oscillation by manipulating the lasing threshold 5,6 .…”

Section: Introductionmentioning

confidence: 99%

Polarimetric parity-time symmetry in a photonic system

Cao

Zhi

et al. 2020

Light Sci Appl

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Parity-time (PT) symmetry has attracted intensive research interest in recent years. PT symmetry is conventionally implemented between two spatially distributed subspaces with identical localized eigenfrequencies and complementary gain and loss coefficients. The implementation is complicated. In this paper, we propose and demonstrate that PT symmetry can be implemented between two subspaces in a single spatial unit based on optical polarimetric diversity. By controlling the polarization states of light in the single spatial unit, the localized eigenfrequencies, gain, loss, and coupling coefficients of two polarimetric loops can be tuned, leading to PT symmetry breaking. As a demonstration, a fiber ring laser based on this concept supporting stable and single-mode lasing without using an ultranarrow bandpass filter is implemented.

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“…High power fiber lasers are urgently needed in industrial manufacture, beam combination, and many other application areas due to their advantages of high conversion efficiency, excellent beam quality, easy thermal management and reliable stability [1], [2]. In the last decade, the average output power of fiber lasers have experienced a rapidly boost owing to dramatic advances in large mode area (LMA) double-clad fiber fabrication technology and development of key components including highbrightness laser diode (LD) [3]- [7]. Generally, there are two structures that can achieve high power fiber lasers, one is master oscillator power amplifier (MOPA) and the other is directly based on a single-stage monolithic fiber laser oscillator.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of 5-kW High-Stability Monolithic Fiber Laser Oscillator With or Without External Feedback

Shi

et al. 2019

IEEE Photonics J.

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In this paper, we construct a high power monolithic fiber laser oscillator based on a commercial ytterbium-doped fiber with core/inner cladding diameter of 25/400 µm. The output performances of the fiber oscillator are experimentally investigated in the conditions of either with or without an external feedback. In the presence of external feedback, a very strong stimulated Raman scattering (SRS) (∼9 dB below the signal light) emerges at the output power of ∼3.56 kW, where the onset of the transverse mode instability (TMI) limits further power scaling. By large angle cleaving the signal arm of the forward combiner to avoid external feedback, the maximum output power of 5.07 kW is achieved with no sign of TMI. The Raman stokes light is ∼35 dB below the signal light and the M 2 factor is measured to be ∼1.6. To directly characterize its power stability and engineering capability, the fiber oscillator is tested for continuous 5-h operation at ∼5.07 kW with power fluctuation less than 0.42%. During the test process, the output power, spectrum, beam quality, and temporal signal perform excellent stability. The experimental results reveal that thresholds of SRS and TMI strongly depend on the external feedback in high power fiber oscillators.

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Narrow linewidth, single mode 3 kW average power from a directly diode pumped ytterbium-doped low NA fiber amplifier

Cited by 115 publications

References 18 publications

Transverse mode instability analysis in fiber amplifiers

Transverse mode instability analysis in fiber amplifiers

Polarimetric parity-time symmetry in a photonic system

Experimental Study of 5-kW High-Stability Monolithic Fiber Laser Oscillator With or Without External Feedback

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