Distributed type fiber optic sensor based on optical fiber cavity attenuation and vibration technique

Abstract

The invention relates to a distributing optical fiber sensor based on the fiber cavity ring-down technology, characterized in that, a laser outical source is connected with an optical fiber spliter connected with a plurality of adjustable optical attenuators; a first optical fiber ring is connected with an adjustable optical attenuator, and the other optical fiber rings are connected with the corresponding adjustable optical attenuators through the revelent optical fiber delay line; a plurality of output ends of the optical fiber ring are connected with the optical fiber combiner which is connected with a high speed photodetector, a high speed A / D conversion and signal process module in turn; the optical fiber ring is respectively connected with an optical fiber coupler at the upper and lower two ends of the ring optical fiber, while the left side and he right side are respectively connected with a single-mode fiber optical fiber and an optical fiber sensing elements. The invention has the beneficial effect that, the measurement of the intensity or the wavelength is converted to that of the optical fiber ring ring-down time, which realizes the one time of measurement is just the millisecond magnitude with simple demodulation method, and easily realizes the distributing optical fiber sensor to measure a plurality of physical quantity at the same time.

Description

technical field [0001] The invention relates to a distributed optical fiber sensor based on optical fiber cavity ring down technology, belongs to the field of optical fiber sensors, and relates to a design of a distributed optical fiber sensor and a demodulation method thereof. Background technique [0002] Optical fiber sensing technology is a new type of sensing technology that uses light as the carrier and optical fiber as the medium to perceive and transmit external signals, which developed rapidly with the development of optical fiber and optical fiber communication technology in the 1970s. Compared with traditional mechanical and electronic sensors, fiber optic sensors have the following advantages: (1) high sensitivity and large dynamic range; (2) anti-electromagnetic interference, good electrical insulation, corrosion resistance, and can be used at high temperature and high pressure (3) The sensor head has a simple structure, small size, light weight, and is suitable...

AI Technical Summary

Problems solved by technology

In 2002, in the paper "Cavity-enhanced spectroscopy in optical fibers" (Optics Letters, 2002, 27(21): 1878-1880), Gupta M et al. used a 10m-long single-mode optical fiber cavity with a highly reflective coating on the end face to carry out Research on medium refractive index sensing; in 2004, Tarsa P B et al. used a single-mode optical fiber cavity coated with a high-reflection film on the end face and used as a The bitapered optical fiber of the sensing element has been researched on tension sensing, but the above two methods need to coat the end face of the optical fiber with a high-reflection film, and the processing technology is relatively difficult. In addition, the high-reflection area of ​​the reflective film is generally only a dozen nm, which greatly limits range of laser wavelengths used

However, the methods used in the above documents can only demodulate one fiber grating sensor at a time, which cannot meet the requirements of distributed sensing

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