Mode instabilities in Yb:YAG crystalline fiber amplifiers

Zhu, Shicheng; Li, Jinyan; Li, Li; Sun, Kexiong; Hu, Cong; Shao, Xinyu; Ma, Xiuquan

doi:10.1364/oe.27.035065

Cited by 8 publications

(6 citation statements)

References 40 publications

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“…However, the ratio is significantly larger with larger core diameters and longer fiber lengths. The comparison of YAG and silica published previously by Zhu et al [19] showed a ratio of 27x with a core diameter of 50 µm and length of 1.6 m, and this result was confirmed in the current simulation.…”

Section: Yb:yagsupporting

confidence: 91%

Simulated power scalability for ytterbium, holmium, and thulium-doped crystalline fiber amplifiers

Smith,

Del Barga,

Oliker

et al. 2024

Solid State Lasers XXXIII: Technology and Devices

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It is well documented that the primary limits to power scaling in fiber amplifiers are Stimulated Brillouin Scattering (SBS), Stimulated Raman Scattering (SRS), Thermal Lensing (TL), Transverse Modal Instability (TMI), and Diode Pump Brightness (DPB). These effects are well known in glass host fiber amplifiers and still garner active research in mitigating techniques for higher power scaling. In this paper, we present power thresholds for these limitations in crystalline host fiber amplifiers. We have leveraged a Coupled Mode Theory (CMT) model to simulate and analyze crystalline YAG fiber lasers for multiple dopants and with variation in step-index fiber core diameters and lengths. The dopants of interest are Ytterbium (Yb), Holmium (Ho), Thulium (Tm), and Erbium (Er). We have generated Power Scalability Maps (PSM) with varying fiber lengths and diameters which depicts the influence of the aforementioned limitations. We have leveraged a higher fidelity CMT-based model to develop comprehensive PSMs for crystalline fibers and for Yb, Ho, Tm, and Er dopants. To produce the PSMs for Tm and Er, additional considerations are required. Both Tm and Er have nonlinear energy transfer processes that make predicting the population concentration, given pump and signal intensities, challenging. We applied a specialized fit function based on a sigmoidal structure to allow analytic interpolation within the CMT-TMI model to accommodate for the complicated energy transfer effects that occur in Tm and Er. The PSMs serve as references for determining limits and potential of crystalline fibers.

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Section: Yb:yagsupporting

confidence: 91%

Simulated power scalability for ytterbium, holmium, and thulium-doped crystalline fiber amplifiers

Smith,

Del Barga,

Oliker

et al. 2024

Solid State Lasers XXXIII: Technology and Devices

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show abstract

“…Running the simulation with pump power of 100 kW was insufficient to cause a TMI threshold for Yb:YAG, Ho:YAG, and Tm:YAG. The increase in the TMI threshold was >50X between Yb:silica and Yb:YAG, which is an increase to the condition examined by Zhu et al [12] and as mentioned in section 2.2 due to increased thermal conduction from the smaller diameter core. Typical simulation outputs are shown in Figure 4 and 5.…”

Section: Modal Instability Simulation Resultsmentioning

confidence: 49%

“…Other parameters used in the simulation are listed in Table 1. To verify that the Yb:YAG model has been implemented correctly, results of the simulation have been compared against equivalent results previously published by Zhu et al [12]. In both simulations, the pump and signal beams propagated in the same directions, called co-pumping.…”

Section: Yb:yag Model and Verificationmentioning

confidence: 99%

Modeling and simulation of crystalline fiber amplifiers

Smith¹,

Barga²,

Brownsberger³

et al. 2023

Fiber Lasers XX: Technology and Systems

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Individual fiber amplifiers with increased average power while maintaining a narrow spectrum and excellent beam quality, enable power scaling of beam combined systems. To accomplish this, fiber amplifiers must contend with two well-known deleterious processes: thermal modal instability (TMI) and stimulated Brillouin scattering (SBS). Changing the fiber host material from silica glass to crystalline Yttrium Aluminum Garnet (YAG) has been reported as a potential means to increase the SBS and TMI power thresholds due to favorable material properties, mainly increased thermal conductivity and decreased electrostrictive constants. In this report, the development of numerical models to examine nonlinear effects in crystalline YAG fiber is described. Fiber simulation code previously developed at the Air Force Research Laboratory (AFRL) for silica are leveraged for crystalline gain media. Results show TMI threshold for a Ytterbium doped YAG (Yb:YAG) fiber 28 times higher than the equivalent silica fiber, and an increase in SBS threshold by over 250 times in YAG compared to silica. The investigations also include thresholds for Holmium doped YAG (Ho:YAG) and Thulium doped (Tm:YAG), which compare well with published experimental data.

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Section: High Power Fiber Amplifiersmentioning

confidence: 99%

“…[372] To completely eliminate the influence of PD, Nd:YAG crystal can be used as the primary material for fiber. [373] In addition to starting from various sources that affect TMI, we can also choose to bypass TMI, such as using multicore optical fiber. [374] However, the manufacturing process limits the mode field of confined doped fiber and the average power based on this scheme is about 1 kW.…”

Section: Mitigation Strategies Of Tmimentioning

confidence: 99%

High‐Power Laser Systems

Zuo

Xin

2022

Laser & Photonics Reviews

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High‐power laser sources are widely used in industrial precision processing and act as a new platform for strong‐field physics research using peak power over petawatt. This review focuses on realizing high‐energy solid‐state disk and slab systems and the nonlinear‐suppression strategies for high‐power fiber systems using the functional fibers. First, the implementations and enabling technologies of the solid‐state lasers for increasing peak power from gigawatt to petawatt are reviewed. Then the mechanisms and suppression strategies of the deterioration effects (including stimulated Raman scattering, stimulated Brillouin scattering, and transverse mode instability) in various fiber amplifiers are analyzed. At the same time, the mechanism and achievements of the current functional fibers are introduced. Finally, the challenges and perspectives of high‐power solid‐state and fiber amplifiers are summarized.

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Mode instabilities in Yb:YAG crystalline fiber amplifiers

Cited by 8 publications

References 40 publications

Simulated power scalability for ytterbium, holmium, and thulium-doped crystalline fiber amplifiers

Simulated power scalability for ytterbium, holmium, and thulium-doped crystalline fiber amplifiers

Modeling and simulation of crystalline fiber amplifiers

High‐Power Laser Systems

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