Few-mode fiber Bragg grating capable of suppressing high-order mode reflection and laser system

A Bragg grating, few-mode fiber technology, applied in lasers, cladding fibers, optical waveguides, etc., can solve problems such as threshold drop, unfavorable increase in output power, oscillator mode instability, etc.

Pending Publication Date: 2020-10-30
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

Both of these processes will reduce the mode instability threshold of the oscillator, which is not conducive to the improvement of output power.

Method used

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  • Few-mode fiber Bragg grating capable of suppressing high-order mode reflection and laser system
  • Few-mode fiber Bragg grating capable of suppressing high-order mode reflection and laser system
  • Few-mode fiber Bragg grating capable of suppressing high-order mode reflection and laser system

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Embodiment Construction

[0025] In order to make the technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

[0026] The present invention uses the overlapping degree of the transverse end face refractive index modulation region of the few-mode fiber Bragg grating and different modes to regulate the self-coupling coefficient of each mode and the mutual coupling coefficient between modes, thereby realizing the effect of the few-mode fiber Bragg grating on the LP 01 mode has higher reflection while the LP 11 The reflectivity of the mode is low. This kind of few-mode fiber Bragg grating capable of filtering out high-order modes can be realized by femtosecond laser face-to-face writing or dynamic writing combined wi...

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Abstract

The invention provides a few-mode fiber Bragg grating capable of inhibiting high-order mode reflection and a laser system. A circular refractive index modulation area concentric with a fiber core is arranged in the fiber core of the few-mode optical fiber, the radius of the refractive index modulation area is smaller than that of the fiber core, the refractive index modulation area and an opticalfiber vector mode are both in circular symmetry, an LP01 mode and an LP11 mode cannot be mutually coupled, and energy exchange cannot occur in the LP01 mode and the LP11 mode. The self-coupling coefficient of the LP11 mode is lower than that of the LP01 mode, and the reflectivity of the LP11 mode is lower than that of the LP01 mode, so that reflection suppression of the LP11 mode is realized. Thefew-mode fiber Bragg grating can be used for a high-power fiber laser oscillator to serve as an endoscope, light reflection can be achieved, and mode regulation and control can also be achieved.

Description

technical field [0001] The invention relates to the technical field of fiber gratings, in particular to a few-mode fiber Bragg grating capable of suppressing high-order mode reflection and a laser system. Background technique [0002] In recent years, with the continuous improvement of power, beam quality and efficiency, high-power fiber lasers have played an increasingly important role in advanced manufacturing, national defense and other fields. In general, high-power fiber laser systems have two structures, namely fiber amplifiers and fiber oscillators. Among them, the fiber optic oscillator has the advantages of simple structure, stable system, and relatively low cost. In recent years, it has received more and more attention, and the output power level has achieved rapid growth. The maximum output power of the reported fiber optic oscillator has exceeded 8kW, and may break through 10kW soon. However, stimulated Raman scattering and mode instability effects are the key ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B6/02H01S3/067
CPCG02B6/02076H01S3/0675
Inventor 王泽锋李宏业王蒙饶斌裕田鑫赵晓帆胡琪浩奚小明陈子伦潘志勇王小林许晓军陈金宝
Owner NAT UNIV OF DEFENSE TECH
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