Large-range high-precision fiber bragg grating sensing method and device based on optical cavity ring-down

Abstract

The invention relates to a large-range high-precision fiber bragg grating sensing method and device based on optical cavity ring-down. The device comprises an LED broadband light source, a signal generator, a 2*1 optical fiber coupler, a transmission optical fiber, an optical fiber delay line, a circulator, a fiber bragg grating FBG, an edge filter, a photoelectric detector, a fiber bragg grating,a PC and an oscilloscope. Fiber optic ring cavity ring-down (FLRD) techniques are used. A spectrum of the broadband light source has a certain range, and when the fiber bragg grating is influenced byexternal parameters and wavelength conversion occurs, effective reflected light can be generated. The edge filter can enable the light intensity passing through the edge filter to be in linear one-to-one correspondence with the wavelength of the fiber bragg grating so that an output loss in the cavity is in linear relation with the wavelength of the fiber bragg grating. Because the ring-down timeis determined by the loss in the cavity, the parameters acting on the fiber bragg grating can be effectively measured by measuring the ring-down time so that large-range and high-precision measurement is realized.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a large-range and high-precision optical fiber grating sensing method and device based on optical cavity ringdown. Background technique [0002] Fiber Bragg grating uses the photosensitivity of the fiber material to write the coherent field pattern of the incident light into the fiber core by means of ultraviolet light exposure, and produces a periodic change in the refractive index along the axis of the fiber core in the fiber core, thereby forming a permanent space. Phase grating, its function is to form a narrow-band (transmission or reflection) edge filter or mirror in the fiber core. In actual measurement, the fiber grating is equivalent to forming a narrow-band edge filter inside the optical fiber to reflect back the light with a specific central wavelength. When the external physical quantity changes, its effective refractive index and grating per...

AI Technical Summary

Problems solved by technology

[0005] In order to overcome the problem that the sensing system of the above-mentioned fiber ring ring down (FLRD) technology cannot measure in a large range

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