Interferometric optical fiber sensor based on eccentric structure and manufacturing method thereof

Abstract

The invention discloses an interferometric fiber-optical sensor based on a core shift structure. The interferometric fiber-optical sensor based on the core shift structure comprises introducing single-mode optical fibers, sensing single-mode optical fibers, multimode optical fibers, leading-out single-mode optical fibers and a spectrograph. The introducing single-mode optical fibers are used for receiving and transmitting light beams from a light source, and outputting the light beams to the sensing single-mode optical fibers. The sensing single-mode optical fibers are in core shift fusion welding relative to the introducing single-mode optical fibers and are used for generating interference and enabling the interfered mode to be coupled to the multimode optical fibers. The multimode optical fibers enable the interfered mode to be coupled to the introducing single-mode optical fibers so as to achieve outputting. The spectrograph is used for executing transmitted spectrum detection on the interfered mode output by the introducing single-mode optical fibers and obtains sensing data correspondingly according to a detection result. The invention further discloses a corresponding manufacturing method. By means of the interferometric fiber-optical sensor based on the core shift structure and the manufacturing method thereof, indeterminacy caused by the offset direction is effectively avoided, the extinction ratio of the entire sensing system can be improved obviously, and meanwhile an optical fiber sensor which is high in sensitivity and convenient to manufacture and package is obtained.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensors, and more particularly, relates to an interference type optical fiber sensor based on an eccentric structure and a manufacturing method thereof. Background technique [0002] Optical fiber sensing for parameters such as refractive index and temperature of the external environment has been widely used in many technical fields such as biology and chemistry, and is becoming one of the most popular measurement technologies today. Optical fiber interferometric sensors based on multimode interference theory have always been popular because of their small size, high sensitivity, anti-electromagnetic interference, high temperature and corrosion resistance. However, for the current interferometric sensor based on the eccentric structure at both ends, it has strict requirements on the offset direction of the eccentric structure at both ends, otherwise the spectral extinction ratio of the struc...

AI Technical Summary

Problems solved by technology

However, for the current interferometric sensor based on the two-end eccentric structure, it has strict requirements on the offset direction of the two-end eccentric structure, otherwise the spectral extinction ratio of the structure is almost zero, and it is difficult to be used for sensor Sensing measurement; In addition, it is very difficult to judge whether the two eccentric directions are consistent, so the sensor needs to be fabricated many times to meet the requirements of sensing measurement

[0003] In view of the above problems, Tian Zhaobin et al. (see "Refractive index sensor based on onanaruptta per Michelson interferometer in a single-mode fiber", Optics Letters, Vol.33, Issue 10, 1105-1107 (2008)) proposed a single-mode optical fiber sensor based on an eccentric structure, that is, the end of the sensing fiber is plated The upper layer of 500nm thick metal film constitutes the sensor of Michelson structure, in this way to avoid the influence of two eccentric directions on the spectral extinction ratio; when the offset of this structure is 6μm, the extinction ratio of the transmission spectrum is above 9db , the spectrum at this time is sufficient for sensing and detection, and the sensitivity is also high; but this structure needs to coat the end face of the optical fiber, and the metal material used is gold, which is not only difficult to manufacture, but also relatively expensive

Yin Guolu et al. (see "RefractveindexsensorwithasymmetricalfiberMach-Zehnderinterfromometerbasedonconcatenatingsingle-modeabrupttaperadcore-offsetsection", Optics&LaserTechnology, 45(2013) 294-300) proposed a solution to add a tapered structure to the front end of the eccentric structure, and the obtained optical fiber sensor has a refractive index sensitivity of The highest can reach 51.2nm / RIU, but while improving the sensitivity of the refractive index, due to the addition of a tapered structure, it will cause the defect that the mechanical structure of the entire system is unstable, and it is difficult to package during processing

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