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Based On The Fiber Interferometric Structure And Bragg Grating To Research Dual-parameters Of Sensor

Posted on:2018-10-01Degree:MasterType:Thesis
Country:ChinaCandidate:H LiuFull Text:PDF
GTID:2348330515957789Subject:Optics
Abstract/Summary:PDF Full Text Request
Fiber optic sensors benefit from their own advantages,widely used in environmental monitoring and industrial production.A fiber sensing structure can sense a single parameter to achieve temperature,strain,bending,refractive index and level measurement so on.However,the fiber sensor itself is inherently sensitive to the temperature.When the temperature changes in a larger range,the single parameter sensor structure on the temperature sensitivity problem will be highlighted.Based on the fiber grating and interference type fiber structure of the dual-parameter fiber sensor can better distinguish between temperature and other parameters of the change.In this paper,two kinds of dual-parameter optical fiber sensors are fabricated by cascade and etching Bragg grating on the fiber interference structure,and the sensing performance is analyzed theoretically and experimentally.The dual-parameter fiber optic sensor is formed by cascading and etching a fiber Bragg grating of a fiber interference structure,and in the optical fiber interference structure is formed by arc discharge welding.As a result,temperature and strain sensors that can operate at high temperatures of 600?,which is obtained by cascading the regenerated gratings.The method of etching the Bragg grating on the photonic crystal fiber core is proposed to realize a high sensitivity temperature and curvature measurement sensor.The details are as follows:Using the inner diameter of 19?m,30?m and 75?m hollow fiber to produce three Fabry-Perot interference fiber structures.Analysis of the corresponding spectrum to get the larger hollow diameter of fiber more easily excited high-order mode,and then its temperature and strain response will be more sensitive.In the experiment,the corresponding temperature sensitivity increased from 0.82pm/? to 0.99pm/?,while the strain sensitivity increased from 1.23pm/?? to 2.36pm/??,which should be the above theoretical analysis.In order to fabricate a stable high temperature and strain dual-parametric sensor,a fiber interference structure made of 19?m hollow fiber is cascaded after fiber Bragg grating.The sensor temperature and strain measurement range were 19?600? and 0?600??,and its characteristic matrix conditions for the 12.09.The optical fiber interference structure based on the Mach-Zehnder interference principle is designed and fabricated by welding multimode fiber at both ends of six-hole thick grapefruit-type photonic crystal fiber.Due to the existence of core mismatch between multimode fiber and photonic crystal fiber,this will excited a lot of high-order mode,so as to improve the temperature and bending response sensitivity.In order to realize the simultaneous measurement of temperature and bending,a fiber Bragg grating is written on the core of the photonic crystal fiber in the fiber interference structure to fabricate a temperature-bending dual-parametric sensor.The experimental results show that the sensitivity of the sensor is-1.03nm/m-1 in the range of 10?22.4m-1,which is 343 times of the bending sensitivity of the Bragg grating.In 8? to 100? the temperature sensitivity is 60.3 pm/?.
Keywords/Search Tags:Fiber Bragg grating, fiber Fabry-Perot interference sensor, fiber Mach-Zehnder interference sensor, high-temperature dual-parameters sensor
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