Bend-insensitive photosensitive optical fiber for online preparation of weak grating array and preparation method

Abstract

The invention discloses a bent insensitive photosensitive optical fiber for preparing a weak grating array online and a preparation method. The optical fiber is a germanium-doped type optical fiber; the refractive index distribution type of the optical fiber is a step type; the content of germanium doped in the core layer of the optical fiber, by weight percentage, ranges from 6.5% to 9%; the value added of the refractive index of the core layer ranges from 0.5% to 0.7% compared with that of a cladding layer; and the bending loss of the optical fiber is smaller than 0.1 dB. The bent insensitive photosensitive optical fiber of the invention can satisfactorily meet the requirements of a weak grating array of which the single-laser pulse inscribing reflectivity ranges from 0.1% to 2% and can be used for large-capacity and long-distance sensing arrays.

Description

technical field [0001] The invention relates to the field of preparation of optical fibers and optical fiber gratings, in particular to a bending-insensitive photosensitive optical fiber for online preparation of weak grating arrays and a preparation method. Background technique [0002] Large-capacity distributed optical fiber sensing systems based on weak reflectivity fiber gratings have broad application prospects. loss and bending loss etc. The method of dynamically and on-line continuous preparation of grating arrays can effectively avoid the insertion loss caused by traditional welding to prepare fiber grating arrays, and is an efficient grating preparation method. [0003] However, the dynamic on-line continuous fabrication of fiber gratings is based on writing fiber gratings with a single laser pulse. Due to the limitations of the writing energy and writing time of a single laser pulse, the first condition for obtaining a certain reflectivity grating is that the op...

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is that the transmission loss of boron-germanium co-doped photosensitive optical fiber in the prior art is large, it is not suitable for the preparation of long-distance, large-capacity weak fiber grating sensing array, and the small-radius bending loss of optical fiber with standard refractive index distribution is large. Disadvantages, as well as the defect that the bend-insensitive optical fiber with a recessed groove in the refractive index is not suitable for the preparation of single-pulse gratings, and provides a combination of the unique characteristics of high refractive index of the core layer of germanium-doped optical fiber and good single-pulse photosensitive performance. On-line fabrication of bend-insensitive photosensitive optical fiber with weak grating array

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