Saddle-shaped gain optical fiber and all-fiber oscillator based on saddle-shaped gain optical fiber

Abstract

The invention provides a saddle-shaped gain optical fiber and an all-fiber oscillator based on the saddle-shaped gain optical fiber. The diameter of a fiber core of the saddle-shaped gain optical fiber is distributed in a manner that the diameter of a middle section is small and the diameters of sections at the two ends are large in the length direction, and the ratio of the diameter of the fiber core to the outer diameter of a cladding is constant in the length direction of the gain optical fiber; therefore, the gain fiber has the capability of simultaneously suppressing a high-order mode and a nonlinear effect. The saddle-shaped gain optical fiber is applied to the optical fiber oscillator so as to suppress the nonlinear effect in the all-fiber oscillator and improve the threshold value of stimulated Raman scattering. An optical fiber end cap is adopted for laser feedback, the thick-end optical fiber of the saddle-shaped gain optical fiber is matched, and the compact structure of the full optical fiber is guaranteed. According to the invention, the advantages of the saddle-shaped gain optical fiber are fully utilized, and the problem that the fiber bragg grating in the saddle-shaped gain optical fiber oscillator structure cannot meet the requirements is effectively solved.

Description

technical field [0001] The invention mainly relates to the field of fiber laser technology, in particular to a saddle-shaped gain fiber and an all-fiber oscillator based on the saddle-shaped gain fiber. Background technique [0002] The fiber optic oscillator has the advantages of simple structure, high reliability, and strong anti-reflection ability, and has great application prospects in the fields of industry and national defense. At present, single-mode all-fiber oscillators based on specially designed partially doped fibers have reached the 8kW level, but the further increase in power is limited by stimulated Raman scattering and mode instability effects. The suppression strategies of the above two physical limitations are quite contradictory, that is, the suppression of the stimulated Raman scattering effect requires a large mode field and a short fiber, while the suppression of the mode instability effect requires the fiber to have fewer supported modes and smaller A...

AI Technical Summary

Problems solved by technology

At present, the single-mode all-fiber oscillator based on a specially designed partially doped fiber has reached the 8kW level, but the further increase in power is limited by the effects of stimulated Raman scattering and mode instability

The suppression strategies of the above two physical limitations are quite contradictory, that is, the suppression of the stimulated Raman scattering effect requires a large mode field and a short fiber, while the suppression of the mode instability effect requires the fiber to have fewer supported modes and smaller Absorption coefficient (corresponding to longer fiber length)

Therefore, it is difficult to continue to increase the power of the all-fiber oscillator using traditional solutions

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