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Interferometer Sensors Based On Long-Period Fiber Gratings

Posted on:2016-11-08Degree:MasterType:Thesis
Country:ChinaCandidate:Z S ZhouFull Text:PDF
GTID:2308330470969633Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Compared with conventional sensors, fiber-optic sensors possess lots of advantages, such as immunity to electromagnetic interference, high temperature resistance, corrosion resistance, small size, high sensitivity, integrated structure,distributed measurement. Because of these unique advantages, fiber-optic sensors have been widely applied to numerous fields, including engineering health monitoring,petrochemical industry, biomedicine, ships and warships, spacecraft. Moreover,fiber-optic sensors will play significant role in the internet of things in the future. This work is mainly based on optical fiber optic sensing, long period fiber grating and fiber optic interferometer technology. The main contents are as follows:1. The development of fiber-optic sensors and the principle as well as applications of long-period fiber gratings(LPFGs) are elaborated. The development status of interferometer sensors based on LPFGs is analyzed.2. The classification and fundamental theory of LPFGs are analyzed. Numerical modeling of LPFGs is conducted. The relation between writing period and length with the transmission is stimulated and discussed.3. The fabrication methods of LPFGs are elaborated. LPFGs used for experiments are fabricated practically.4.A novel interferometer sensor based on a LPFG and core offset is proposed. The interference occurs between the cladding mode which is excited by the LPFG and travels for a distance with the core mode at core offset. With the variation of the lateral force and curve applied to the misaligned point, the extinction ratio or the interference phase changes. Accordingly the two parameters can be sensed. Moreover,the interferometer can be applied to measure refractive index as well.5.An interferometer sensor based on a waist-enlarge splicing with LPFG has been proposed. The interference occurs between the cladding mode which is excited by the LPFG and travels for a distance with the core mode at waist-enlarge point. With the variation of the lateral force and curve applied to the waist-enlarge point, the interference phase or extinction ratio changes. The proposed sensor is proved to has the advantages of simple structure, low cost, and high sensitivity.
Keywords/Search Tags:Fiber optic sensor, Interferometer sensors, Long-period fiber grating(LPFG), Core offset, Waist-enlarge
PDF Full Text Request
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