Thermotropic ultra-large mode field fiber

Abstract

The invention discloses a thermotropic ultra-large mode field fiber, and aims to solve the problem of reduced and limited numerical value and aperture of a fiber core and big manufacturing difficulty. The thermotropic ultra-large mode field fiber is composed of the fiber core and a coating layer; the refractive index of the fiber core material is increased along with the temperature increase, and the fiber core includes an inner fiber core and an outer fiber core, and the inner fiber core is located at the center of the outer fiber core, the refractive index of the inner fiber core is less than or equal to the refractive index of the outer fiber core; a gain medium is mixed in the inner fiber core, and the outer fiber core excludes gain medium; the diameter of the inner fiber core is more than or equal to 20 microns, the ratio between the diameter of the inner fiber core and the diameter of the outer fiber core is less than or equal to 50%; the coating layer excludes the gain medium, and includes an inner coating layer and an outer coating layer; the outer coating layer coats the inner coating layer, and the inner coating layer coats the outer fiber core; the refractive index of the inner coating layer is less than that of the outer fiber core; the refractive index of the outer coating layer is less than the refractive index of the inner coating layer. The numerical value and aperture of the inner fiber core are further reduced, the manufacturing difficulty is lowered, and the light filtering pressure of the coating layer is released.

Description

technical field [0001] The invention relates to the technical field of lasers. In particular, it relates to an active optical fiber that realizes a waveguide structure based on thermal effects, can realize ultra-large mode field laser output, and has a simple manufacturing process. Background technique [0002] Fiber laser has the characteristics of light weight, compact structure, long life, good beam quality, strong anti-interference ability, etc. It has a wide range of applications in the fields of communication, sensing, machining, medical treatment, scientific research, and national defense and military. Especially with the rapid development of the power level of fiber lasers in recent years, the application range of fiber lasers is also expanding, and the degree of attention is getting higher and higher. Although the power level of fiber lasers has developed by leaps and bounds, it has reached the order of 10kW. However, the further improvement of the power level of ...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to solve the problem that the reduction of the numerical aperture of the fiber core is limited in the first solution, and increase the core diameter of the optical fiber without introducing microstructures, so as to solve the problem caused by the introduction of microstructures in the second solution. The problem of difficulty in production caused by the structure

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