High power femtosecond chirped pulse amplification in large mode area photonic bandgap Bragg fibers

International audienceWe report on high power amplification of femtosecond pulses in 40-μm core diameter Yb-doped photonic bandgap Bragg fibers. The robustness to bending and transverse spatial behavior of these fibers is analyzed through simulations. The fibers are used in both stages of a moderately stretched (150 ps) femtosecond chirped pulsed amplification (CPA) system. A compressed average power of 6.3W is obtained using a low-index polymer-coated Bragg fiber with excellent beam quality and high efficiency, in agreement with numerical simulations. The use of an air-clad Bragg fiber allows us to scale the output power to 47 W at a repetition rate of 35MHz. This experiment demonstrates the great potential of Bragg fibers to increase the mode area and the power of practical bending-tolerant femtosecond fiber systems

Solid-core photonic bandgap fibers for high-power fiber lasers

International audienceAn overview of various designs of large-mode-area photonic bandgap fibers (PBGFs) is presented in this paper. Bending properties of these structures are discussed and compared with those of step-index and air-silica microstructured fibers. Peculiarities of active PBGF fabrication are considered, and novel high-power laser architecture based on such fibers is described

Génération de supercontinuum dans une fibre à bande interdite photonique

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Tight control of the spectral broadening obtained by nonlinear conversion in a photonic bandgap fiber

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100 W émis en régime continu en sortie d'un laser à fibre à bande interdite photonique de bragg

National audienceL'émission en régime continu d'une puissance de 100 W en sortie d'un laser à fibre LMA de Bragg est rapportée. Une pente d'efficacité de 81 % a été obtenue (en fonction de la puissance injectée) pour un laser à fibre souple pouvant être courbée sans dégradation des performances jusqu'à un rayon de courbure de 7,5cm

Increasing the SBS threshold in single-mode step-index optical fiber by design of highly multimode acoustic profile

The stimulated Brillouin scattering (SBS) is the main power limiting factor in the high-power narrow-line fiber laser circuits. A good way to increase the SBS power-threshold is to reduce its coherent gain, which is directly connected with the width of the Brillouin gain spectrum (BGS). The Brillouin gain peak and the phonons life-time are inversely proportional to the full-width-at-half-maximum of the BGS. The fine structure of the BGS and its ranges are sufficiently affected by parameters of the acoustic waveguide of the fiber. We propose a novel approach for increasing the BGS width and lowering its maximum (related directly to the SBS threshold) for a given optical refractive index profile. The aim of the approach is to maximize both the number and spectral spread of guided acoustic modes, as well as equate the acousto-optic interaction coefficients (acousto-optical overlap integrals) for the maximum possible number of these modes. This is due to the fact that an increase in the number of acoustic modes effectively contributing to the BGS, while preserving the distribution of the optical mode intensity, causes the scattered Stokes optical power to be redistributed accordingly between the corresponding number of Brillouin spectral lines, providing proportional damping of the Brillouin gain. Such an acoustically multimode SBS suppression can be achieved by tailoring a proper radial acoustic refractive index profile which can be fabricated by co-doping of silica with phosphorous oxide and fluorine. © 2021 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Effect of polymer coato,ng on leakage losses in Bragg fibers

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Polarization-maintaining photonic bandgap Bragg fiber

International audienceThe possibility of fabricating a polarization-maintaining Bragg fiber has been studied. It is shown that violation of the cylindrical symmetry of a Bragg mirror in most cases results in a sharp increase in optical loss, which is caused by resonance transmission through the Bragg mirror at wavelengths near the cutoffs of the modes of the high-index rings with a nonzero azimuthal index. It is shown that placing stress-applied parts or air holes inside the Bragg fiber core allows one to avoid this effect. A polarization-maintaining Bragg fiber with perfect light confinement in the core is demonstrated for the first time to our knowledge

Photonic Bandgap Fibers for High-Power CW and Pulsed Applications

paper Tu.D3.1International audienc