Demonstration of fundamental mode only propagation in highly multimode fibre for high power EDFAs

Stacey, Craig D.; Jenkins, R. M.; Banerji, J.; Davies, Annette

doi:10.1016/j.optcom.2006.08.002

Cited by 18 publications

(7 citation statements)

References 12 publications

(17 reference statements)

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“…The excitation of the single LP 07 mode by using a long period fiber Bragg grating (LPG) in a multimode fiber with an 86-m core was demonstrated 9 . The fundamental mode propagations through a 20-cm long straight piece of fiber with 300 m core diameter and NA=0.39 10 and through a 2-m long fiber with a 100-m core diameter and an output beam factor of M 2 =1.6 11 have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…These results led to the imperative conclusion: the mode coupling in fibers with a sufficiently large cladding diameter could be low; consequently, any guided mode excited by selective launching can propagate in a highly multimode core over long distance without notable mode conversion [8][9][10][11] .The selective mode coupling in a multi-mode uniform cylindrical fiber has an attractive alternative -an adiabatic fiber tapering. In this technique, the multimode fiber is tapered down to a single-mode size used as a launching port for a fundamental mode excitation.…”

Section: Introductionmentioning

confidence: 99%

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Fundamental mode evolution in long, large-core (>100 μm) adiabatic tapers

Kerttula

Филиппов

Chamorovskii

et al. 2013

Fiber Lasers X: Technology, Systems, and Applications

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We have experimentally investigated fundamental mode propagation in few-meter-long adiabatic step-index tapers with high numerical aperture, core diameter up to 117 m (V=38), and tapering ratio up to 18. We confirmed single fundamental mode guiding in tapers with uniform core index profile by several experiments. We observed an annular near field distribution and degraded beam quality for large output core diameters, found to occur due to intrinsic mechanical stress in the fibers. We expect that eliminating the stress would prevent the mode deformation and allow constructing single-mode, diffraction-limited tapered large-mode-area amplifiers with a good beam shape.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fundamental mode evolution in long, large-core (>100 μm) adiabatic tapers

Kerttula

Филиппов

Chamorovskii

et al. 2013

Fiber Lasers X: Technology, Systems, and Applications

View full text Add to dashboard Cite

show abstract

“…For short (~10 cm) PG fibers, this technique is not available, and therefore inherently single-mode fibers with low numerical apertures have been employed in the past [3]. Alternatively, the lowest-order mode can be excited selectively under proper launching conditions, and the lowest order mode can propagate for substantial lengths (>> 10 cm) if the fiber remains straight and uniform [7]. The fibers used for the work presented here were generally multimode, and selective amplification of the lowest order mode in short straight fibers was demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Large core highly doped fiber amplifiers.

Dansson¹,

Moore²,

Soh³

et al. 2012

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We have demonstrated amplification of nanosecond optical pulses to the millijoule level using ytterbium-doped phosphate glass fibers. Fibers with 35 um and 49 um diameter cores produced up to 700 uJ and 2.25 mJ pulses, respectively, with pulse durations less than 10 ns. By tapering the diameter of the fiber from single-mode to multi-mode, we were able to produce output with a nearly lowest-order-mode spatial profile in 35 um-core fibers that were inherently multimode. We report on progress in five areas of amplifier development: (1) pulse energy, (2) fundamental mode propagation in multi-mode fibers, (3) phosphate glass fiber processing, (4) highly doped gain fiber modeling, and (5) amplification of single-frequency pulses at 2 um wavelength. 4 ACKNOWLEDGMENTS

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“…cleaving, splicing and tapering). Several groups have already shown the possibility to maintain a diffraction-limited beam along the propagation through multimode fibers with core diameters of a few hundred micrometers and short fiber lengths of several tens of centimeters to up to two meters [5], [6], with core diameters of some tens of micrometers and fiber lengths of ten to twenty meters [7]- [9], or in few-mode fibers with a length of hundred meters or more [10]- [12]. These results show that there is a tradeoff between the size of the core and the length of the fiber.…”

mentioning

confidence: 99%

Preserving Nearly Diffraction-Limited Beam Quality Over Several Hundred Meters of Transmission Through Highly Multimode Fibers

Röhrer

Codemard

Kleem

et al. 2019

J. Lightwave Technol.

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The influence of the core diameter and the fiber length on the beam quality of the transmitted beam was investigated theoretically and experimentally for highly multimode step-index fibers with a numerical aperture of 0.22 using a fully monolithic setup. We show that it is possible to maintain a nearly diffraction-limited beam quality (M 2 ≈ 1.3) through 100 m long multimode fibers. For a core diameter of 60 µm and a fiber length of 380 m one can still deliver a beam with an M 2 value of 2.1. The high-power suitability of this approach was shown by transmitting 1 kW of power through a 100 m long fiber with a core diameter of 60 µm without the onset of stimulated Raman scattering while maintaining a nearly diffraction-limited beam quality (M 2 ≈ 1.3). Index Terms-Large mode area (LMA), multimode step-index fiber, nearly diffraction-limited beam, stimulated Raman scattering (SRS). I. INTRODUCTION F OR laser materials processing optical fibers offer a flexible solution for transporting the laser beam from the laser source to the work piece. The fiber delivery of high-brightness solid-state laser radiation is however limited by to the onset of nonlinear effects. The output of industrial high-power cw fiber lasers typically exhibits a broad spectral bandwidth [1], thus the dominant nonlinearity in the delivery fibers is stimulated Raman scattering (SRS) [2]. The threshold power leading to SRS is proportional to the ratio between the effective mode field area and the fiber length [3]. To overcome SRS and enable the fiber-optic transmission of high-power laser beams over long distances the core size must be enlarged, thus making the fiber multimode.

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Demonstration of fundamental mode only propagation in highly multimode fibre for high power EDFAs

Cited by 18 publications

References 12 publications

Fundamental mode evolution in long, large-core (>100 μm) adiabatic tapers

Fundamental mode evolution in long, large-core (>100 μm) adiabatic tapers

Large core highly doped fiber amplifiers.

Preserving Nearly Diffraction-Limited Beam Quality Over Several Hundred Meters of Transmission Through Highly Multimode Fibers

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