Ultra-low fiber bragg grating sensing system and query method thereof

Abstract

The invention relates to an ultra-low fiber bragg grating sensing system and a query method thereof. The ultra-low fiber bragg grating sensing system is mainly composed of a narrow-band tunable laser, a modulation module, an annular device, a fiber bragg grating array, a sampling module, a photoelectric detector and a data processing computer, wherein each of the modulation module and the sampling module comprises a SOA (Service Oriented Architecture) high-speed photoelectric switch; the modulation module and the sampling module are driven by different channels of a same signal generator; a phase difference exists between two paths of driving pulses; the fiber bragg grating array is composed of identical fiber bragg gratings with ultra-low reflectivity; and a scanning laser is taken as a light source and an accurate time division technology is combined for isolating crosstalk between gratings, so that the effective query for the fiber bragg grating with the ultra-low reflectivity is realized. The ultra-low fiber bragg grating sensing system provided by the invention has the characteristics of high capacity, high response speed, high flexibility and low cost; the quantity of the fiber bragg gratings with the ultra-low reflectivity serially connected with one optical fiber can be tens of thousands; and the application value is high.

Description

technical field [0001] The invention belongs to the field of sensing technology, and in particular relates to an extremely weak fiber grating sensing system and a query method thereof. Background technique [0002] Optical fiber sensors have the characteristics of fire and explosion protection, corrosion resistance, and anti-electromagnetic interference, and have a wider application range than other sensors. With the rapid development of grating writing technology, by writing gratings during the fiber drawing process, the complex operation of splicing multiple gratings one by one on an optical fiber in the traditional process is overcome, and the limitation of the number of gratings by splicing loss is avoided. Writing any number of gratings on an optical fiber provides a material basis for ultra-large-capacity fiber grating sensing and monitoring. [0003] Ordinary gratings have high reflectivity, and the optical power attenuates quickly after being reflected by multiple g...

AI Technical Summary

Problems solved by technology

Multi-grating reflection cannot be completely avoided by using traditional time domain detection technology (Patent No. 201010590361.8 "Sensing Multiplexing System Based on Unequally Spaced Weak Bragg Reflection Fiber Bragg Grating Array"; Patent No. 201110373500.6 "Distributed Sensing Network and The precise positioning method of each FBG"), the signal processing equipment is complex, and the minimum reflectivity and maximum multiplexing number of the grating are severely limited; when the reflectivity of the grating is high, the reflection of the front grating will be Faster reduction of the optical power corresponding to the Bragg wavelength will significantly reduce the peak power reflected by the subsequent grating, and the reflected pulse will have a "flat-top" phenomenon, the so-called "shadow effect", which will cause difficulties in judgment and limit the maximum number of multiplexed gratings

In addition, the same multi-grating series query requires accurate time division multiplexing, and the real-time detection speed of reflected pulses reaches ns level. The existing high-speed signal processing circuits or analog electronic switch circuits have obvious time delays, and cannot accurately detect and process reflected pulses. Pulse signal, related technologies disclosed (Patent No. 201110326745.3 "Fiber Bragg Grating Sensing Method and System Based on WDM Multi-channel Output Time Domain Address Query Technology"; Patent No. 200610009939.X "CPLD-Based Time Division Multiplexing Fiber Bragg Grating Sensitivity test system") needs to keep the distance between the gratings at tens of meters, there are obvious defects, and there is no crosstalk between isolated pulses, the system is complex and the performance is poor, the cost is expensive, and there are no reports of related applications

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