High-order mode suppression in double-clad optical fibers by adding absorbing inclusions

Aleshkina, Svetlana S.; Kochergina, Tatyana A.; Velmiskin, Vladimir V.; Bobkov, Konstantin K.; Bubnov, M M; Yashkov, Mikhail V.; Lipatov, Denis S.; Salganskii, M.Y.; Guryanov, A. N.; Likhachev, Mikhail E.

doi:10.1038/s41598-020-63969-7

Cited by 15 publications

(4 citation statements)

References 25 publications

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“…This is a wellknown factor that could improve the PCE in fiber lasers that operate near 976 nm [1][2][3]7]. With our fiber design, this method could be used even more efficiently due to the tight fiber bending (and the filtering of high order modes) and the additional loss of high-order mode loss due to coupling with high-index rods [13]. Our calculations show that increasing the core diameter to 18 µm will result in an additional increase in PCE of about 1.5 times (see blue curve).…”

Section: Discussionmentioning

confidence: 99%

Improvement of Efficiency in 976 nm Fiber Amplifier by Spectral Filtering in Yb-Doped Fiber with Absorbing Rods Embedded in the Cladding

Aleshkina,

Davydov,

Velmiskin

et al. 2024

Photonics

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A novel Yb-doped fiber design for improved lasing near 976 nm based on spectral filtering of the amplified spontaneous emission near 1030 nm was realized and investigated. A very sharp short-pass filter was implemented by adding appropriately chosen high-index absorbing rods into the silica cladding. In this case, the resonant interaction of the core mode with the high-index rod mode could be controlled by fiber bending, which allows for the precise adjustment of the stop-band position. It was shown that the utilization of Sm-doped absorbing rods allows one to achieve very high absorption of emission at unwanted wavelengths, but it also adds background losses for the pump near 915 nm and for the signal at 976 nm. Despite this fact, the improvement of efficiency in the 976 nm fiber amplifier, after shifting the stop-band to 1000 nm, was clearly demonstrated. Based on theoretical calculations, it was shown that, after optimizing the fiber parameters, a further twofold improvement in efficiency was possible despite the excess losses at the pump and signal wavelengths.

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Section: Discussionmentioning

confidence: 99%

Improvement of Efficiency in 976 nm Fiber Amplifier by Spectral Filtering in Yb-Doped Fiber with Absorbing Rods Embedded in the Cladding

Aleshkina,

Davydov,

Velmiskin

et al. 2024

Photonics

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“…As mentioned above, these structures can be used as a sensing element for a fiber optic sensor based on a Fabry-Perot interferometer or a fiber optic radiation scatterer [16,17]. For different sensors and optical radiation scatterers, there are different requirements for the geometrical parameters of the internal structure [18,19].…”

Section: Introductionmentioning

confidence: 99%

Mathematical Model of Fuse Effect Initiation in Fiber Core

et al. 2023

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This work focuses on the methods of creating in-fiber devices, such as sensors, filters, and scatterers, using the fiber fuse effect. The effect allows for the creation of structures in a fiber core. However, it is necessary to know exactly how this process works, when the plasma spark occurs, what size it reaches, and how it depends on external parameters such as power and wavelength of radiation. Thus, this present study aims to create the possibility of predicting the consequences of optical breakdown. This paper describes a mathematical model of the optical breakdown initiation in a fiber core based on the thermal conductivity equation. The breakdown generates a plasma spark, which subsequently moves along the fiber. The problem is solved in the axisymmetric formulation. The computational domain consists of four elements with different thermophysical properties at the boundaries of which conjugation conditions are fulfilled. The term describing the heat source in the model is determined by the wavelength of radiation and the refractive indices of the core and the shell and also includes the radiation absorption on the released electrons during the thermal ionization of the quartz glass. The temperature field distributions in the optical fiber are obtained. Based on the calculations, it is possible to estimate the occurrence times of various phase states inside the fiber, in particular, the plasma spark occurrence time.

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“…The 0.5 μm high-index ring in the core can be fabricated using MCVD technique like the absorbing layer with a designed thickness of 0.446 μm in Ref. [31]. The performance of single-mode operation with a large mode area over a range of wavelengths makes the fiber a good candidate for fiber lasers.…”

Section: Introductionmentioning

confidence: 99%

Segmented Cladding Fiber With a High-Index Ring in Core for Wideband Single-Mode Operation in Any Bending Orientation

Guo

Ning

et al. 2021

IEEE Photonics J.

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A resonant-ring-assisted large mode area segmented cladding fiber (RR-SCF) with a high-index ring in the core is proposed. Numerical investigations of the effects of the high-index ring on the leakage losses of guiding modes, mode area, and electric field distribution of FM in the proposed fiber show the high-index ring not only increases the ratio of the loss between the fundamental mode (FM) and the higher-order modes (HOMs) but also improves the electric field distribution of the FM to be flat. By taking these advantages of the high-index-ring-assisted core, the effective single-mode (SM) operation is achieved in the proposed fiber bent in any orientation, which makes up the defect of the conventional RR-SCF that the SM output is affected by the bending orientation. Meanwhile, the mode area is enlarged. Furthermore, the effects of the heat load, duty cycle, bending, and operation wavelength on the fiber performance are analyzed. The results show single-mode operation in all bending orientations with a mode area larger than 824 μm 2 can be achieved at a tight bending radius of 15 cm to 16 cm when the operating wavelength ranges from 1.06 μm to 1.76 μm. This fiber shows great potential in high-power fiber lasers.

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High-order mode suppression in double-clad optical fibers by adding absorbing inclusions

Cited by 15 publications

References 25 publications

Improvement of Efficiency in 976 nm Fiber Amplifier by Spectral Filtering in Yb-Doped Fiber with Absorbing Rods Embedded in the Cladding

Improvement of Efficiency in 976 nm Fiber Amplifier by Spectral Filtering in Yb-Doped Fiber with Absorbing Rods Embedded in the Cladding

Mathematical Model of Fuse Effect Initiation in Fiber Core

Segmented Cladding Fiber With a High-Index Ring in Core for Wideband Single-Mode Operation in Any Bending Orientation

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