Fabrication Of Special Tilted Fiber Bragg Grating And Study Of Its Sensing Characteristics

Tilted fiber grating,as a member of fiber grating family, inherited the tradition ofall the advantages of fiber grating. And their structural characteristics made them shinein the field of fiber optic sensing, making up the traditional fiber grating on a number ofenvironmental helpless parameters, by the way, high sensitivity and high resolution inconcentration and micro-displacement were shown. The traditional ordinary reflectivefiber grating and long period fiber grating transmission type could not match theseadvantages. Along with the development of high-speed fiber-optic sensing technology,tilted grating’s research was inevitable, especially on special tilted fiber Grating sensingcharacteristics. For special tilted fiber grating sensor in this article, studies starts mainlyfrom the following aspects:(1) Fiber grating writing technologies was analyzed, their advantages anddisadvantages were reported, status quo at home and abroad for tilted fiber grating andmultimode tilted fiber grating and its sensing application was researched.(2) FBG sensing working mechanism was studied, the photosensitivity of the fiberused to write grating was discussed. Using the Ge-doped photosensitive fiber to writeFBGs, the reflectivity and the wavelength of the bulk grating written from the statisticalanalysis was appropriate to determine the amount of optical fiber doped withgermanium and fiber photosensitivity high enough or uniform distribution.(3) Based on the grating coupled mode theory and transfer matrix method,common fiber gratings were simulated: uniform fiber Bragg grating, chirped grating,mode coupling between the tilted fiber grating. furthermore, various types of gratingwere also apodised. Simulation contributed to the understanding of the fiber grating,and was a basis for preparation of the multimode tilted grating.(4) Lots of tilted grating written on the graded index multimode optical fiber wereachieved, the impact of the inclination of the size of the grating. Electing tilted2.5°grating as a sensor was also analyzed, studing its temperature, strain, bending sensingcharacteristics. Good linear sensor characteristics and high sensitivity were obtained,with single mode uniform fiber grating sensing characteristics, showing the potential practical value. When one end of the fiber grating sensor was cut smoothly. Thespectrum of such a sensor was changed by fresnel reflection. Temperature sensingperformed with linear feature and significantly high sensitivity, this sensor had a morecompact, useful in some special environment inside the detection.