Cladding light filtering structure and manufacturing method thereof

Abstract

The invention discloses a cladding light filtering structure for filtering out cladding light in a double-cladding or multi-cladding fiber laser system and a manufacturing method of the cladding light filtering structure. The cladding light filtering structure comprises an optical fiber and a filtering material coating layer, wherein a protective layer and an outer cladding layer of the optical fiber are removed, and a section of glass cladding layer is exposed. The refractive index of the filtering materials is higher than the refractive index of the outer cladding layer of the optical fiber, and the coating layer of the filtering materials is the filtering materials and is coated in a subsection mode. Due to the fact that refractive index, coating length and coating space of the filtering materials are matched, filtering quantity of all sections is roughly the same, highest temperature jump of an optical filter in a working state is reduced, reliability of the system is improved, and the more the subsections and the types of the materials are, the better the effect is.

Description

technical field [0001] The invention relates to a fiber laser or a fiber amplifier, in particular to a cladding light filtering structure for a fiber laser or a fiber amplifier and a preparation method thereof. technical background [0002] The output power of fiber lasers continues to increase, and the output power of a single unit of more than 10,000 watts has been achieved. Such a high output power is mainly due to the development of optical fiber and pump source technology. Usually, fiber lasers or fiber amplifiers with an output power exceeding 1 watt use double-clad active fibers as gain fibers. The so-called double-clad optical fiber generally consists of a core 6, a glass cladding 5, a low refractive index outer cladding 4, and an optional polymolecular polymer protective layer 3, such as figure 1 . The low refractive index outer cladding 4 is usually a multimolecular polymer with a refractive index around 1.36. The refractive index of the fiber core 6 is general...

AI Technical Summary

Problems solved by technology

Because the excess cladding light decays approximately exponentially in the filter layer, the above-mentioned coating layer absorbs a lot of heat in the first short period, resulting in excessive local temperature, which greatly limits its filtering ability

[0009] As the output power of fiber lasers or amplifiers continues to increase, the absolute amount of excess inner cladding light that needs to be filtered out is also increasing. Therefore, the centralized coating and filtering scheme of a single material has become one of the bottlenecks that affect the increase in the output power of fiber lasers or fiber amplifiers.

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