Tunable double parallel matched optical fiber raster demodulating system

Abstract

The present invention relates to a tunable double parallel matching fiber-optic grating demodulation system. It is mainly composed of a 1 / 3 coupler, four demodulation fiber-optical gratings, five photoelectric detectors, four light branching units, two wavelength tuners and a computer. Said invention also provides the concrete action of every the above-mention portion and working principle of said tunable double parallel matching fiber-optic grating demodulation system.

Description

technical field [0001] The invention relates to fiber grating sensing, in particular to a tunable double-parallel matching fiber grating demodulation system, which is used for measuring the central wavelength of the narrow-band reflection spectrum of the fiber Bragg grating. Background technique [0002] As an optical device, fiber grating is a device that establishes a periodic distribution of spatial refractive index in the optical fiber, so that the propagation characteristics of light can be changed in it. When a broadband light source is incident on a fiber Bragg grating (hereinafter referred to as FBG), the central wavelength λ of the reflected light B is given by the Bragg equation: [0003] lambda B =2nΛ [0004] Among them, n is the effective refractive index of the fiber core, and Λ is the grating period. [0005] When the physical quantities such as temperature and strain of the FBG's environment change, it will cause changes in the refractive index and period...

AI Technical Summary

Problems solved by technology

[0017] Among the above demodulation methods, the interference demodulation technology has high measurement accuracy, but it measures relative values, and the measurement range is limited by the free spectral range of the interferometer; the signal detection of the tunable light source demodulation technology is convenient and the resolution is high , but the light source is difficult to manufacture and the cost is high; the test range of the linear edge filter demodulation technology is inversely proportional to the resolution, and the linearity of the filter is required to be very good, the slope must be very large, and it is difficult to manufacture; the tunable filter demodulation technology demodulation The range is large, but the scan cycle is long, the test speed is slow, and the repeatability is poor; the matched filter demodulation method is simple and practical, but the demodulation range is too small

Due to the existence of the above shortcomings, wavelength demodulation technology has become one of the main obstacles to the industrialization of FBG sensing technology

The FBG demodulator currently on the market is mainly based on scanning F-P technology and interferometric scanning technology, but its production is complicated and the price is quite expensive

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