Thermal deformation mode-based hollow double-core long-period fiber grating fabrication method

Abstract

The present invention belongs to the optical fiber communication and optical fiber sensing technical field and relates to a thermal deformation mode-based hollow double-core long-period fiber grating fabrication method. The method includes the following steps that: (1) the hollow double-core optical fiber coating layer of a grating to be fabricated is removed, and an obtained hollow double-core optical fiber is fixed through an optical fiber fixture; (2) air inflation or air extraction is performed on the hollow double-core optical fiber, so that the internal air pressure of the optical fiber can be greater than or smaller than external air pressure; (3) the optical fiber is heated for 2s by using a heating component, so that the optical fiber can expand outwards or collapses inwards; (4) a displacement platform is controlled to make the optical fiber move 1mm towards the same direction, and the optical fiber is heated again for 2s; and (5) the step (3) and the step (4) are repeated, so that a periodic structure can be realized, and the fabrication of the long-period fiber grating is realized. According to the method of the invention, only three operation steps, namely, inflation or air extraction, heating or horizontal back-front movement of the optical fiber are adopted, and therefore, the problem of complicated operation of the precise alignment o laser pulses and an optical fiber of an existing fiber grating fabrication method can be avoided.

Description

technical field [0001] The invention belongs to the technical fields of optical fiber communication and optical fiber sensing, and in particular relates to a method for writing hollow double-core long-period optical fiber gratings based on thermal deformation. Background technique [0002] A fiber grating is an optical fiber device that forms a permanent periodic change in the refractive index in the fiber core by a certain method. Long-period fiber gratings are widely used in the fields of communication and optical fiber sensing because of their low insertion loss, small back reflection, and their transmission characteristics are sensitive to changes in temperature, strain, and environmental refractive index. [0003] Hollow dual-core optical fiber is composed of core, annular cladding and air cavity. The air cavity is located in the middle of the annular cladding, and the fiber core is located in the air cavity of the cladding and is fused and embedded on the inner wall o...

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Problems solved by technology

The disadvantage is that it needs to be aligned with the exit position of the laser, CO 2 The focus plane of the laser pulse needs to be precisely perpendicular to the plane formed by the two cores. At the same time, precise control of the rotation angle of the fiber is required, and the operation is cumbersome and the structure is complex (Tingting Yuan, Xing Zhong, Chunying Guan, *Jianan Fu, Jing Yang, Jinhui Shi, and Libo Yuan, Long period fiber grating in two-core hollow eccentric fiber, Optics Express, Vol.23, No.26)

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