Large-mode-field ytterbium-doped optical fiber

Abstract

The invention discloses a large-mode-field ytterbium-doped optical fiber. The optical fiber is provided with a core layer containing ytterbium at least, a glass substrate internal wrapping layer which surrounds the core layer, and a low-refractive-index coating layer which surrounds the glass substrate wrapping layer. Ytterbium concentration of the center of the optical fiber along any diameter direction of the core layer is the highest, and ytterbium concentration gradually reduces from the center to the two end points. Distribution of ytterbium concentration of the core layer along the diameter direction of the core layer meets Gaussian distribution. The optimized optical fiber output light beam quality is acquired by the design without reducing core layer doping concentration or changing bending property or increasing optical fiber preparation difficulty.

Description

technical field [0001] The invention belongs to the field of optical fiber technology, and more specifically relates to a large mode field ytterbium-doped optical fiber. Background technique [0002] When pump light of a certain wavelength is injected into the optical fiber doped with rare earth elements in the core layer, the population inversion will be formed, and stimulated emission will be formed. Therefore, the rare earth-doped fiber is used in the fiber amplifier to amplify the signal light of stimulated radiation, and in the fiber laser, the light of stimulated radiation can be amplified to have exactly the same properties as the signal light due to the function of the resonant cavity. The doping of different rare earth elements can radiate light of different wavelengths under the excitation of corresponding wavelengths, and can cover a large spectral range. [0003] Among them doped with ytterbium (Yb 3+ ) optical fiber is a kind of rare earth doped optical fiber....

AI Technical Summary

Problems solved by technology

[0005] Among the above-mentioned optical fibers that can realize single-mode operation with large mode field area, the bending method is a relatively simple method to filter the mode, but this method is limited to small core diameter fibers. Once the core layer is large or the numerical aperture is low , the bending loss difference between the high-order mode and the base mode is reduced, and the energy leakage caused by the high-power filter mode will cause certain damage to the coating layer, which will seriously cause the coating layer to burn out

The core diameter is drastically reduced by the taper method, and it is easy to cause irreversible damage under high power, so it is difficult to filter out high-order modes by increasing the taper core diameter.

Others such as photonic crystal fiber, high-order mode fiber, and chiral coupling fiber can achieve excellent mode output and improve the quality of the output beam, but the preparation process of each fiber is relatively complicated, and the requirements for the process are extremely high. Large-scale commercial applications need more innovation

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