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Research On High Temperature Sensing Technology Based On Optical Fiber Microstructur

Posted on:2023-06-24Degree:MasterType:Thesis
Country:ChinaCandidate:Y HanFull Text:PDF
GTID:2568306758467514Subject:Optical Engineering
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With the advent of the fourth industrial revolution,people have made great progress in the fields of information transmission,industrial production and intelligent control.Corre-spondingly,higher requirements are put forward for the related industrial base,such as coal,petroleum,electric power and other energy industries,metallurgical industry,basic chemical industry and some machinery.As the tentacles of human perception and monitoring,sensing discipline has occupied an important position in the history of industrial development since its emergence.In the era of the Internet of Everything,basic industries are facing transformation and upgrading.As a new type of sensing technology with high precision,anti-electromagnetic interference and high sensitivity,optical fiber sensing technology meets the needs of the in-formation age and is a future-oriented sensor.Among them,in harsh conditions,such as high temperature,high pressure and other environments,the advantages of the optical fiber sensor’s compact size,certain bending ability,and unaffected transmission are more prominent.With the development of oil exploration and aerospace,high temperature sensor needs more research and experimental data in both stability and sensitivity.This paper mainly studies high-temperature optical fiber sensors,proposes several optical fiber microstructures with high-performance sens-ing properties,and verifies several ideas for improving the performance of high-temperature optical fiber sensors.The sensing characteristics of the high temperature sensor are studied in detail.The main innovations are as follows:(1)In this paper,an optical fiber sensor based on Si O2microsphere array and air cavity was fabricated by a fiber fusion splicer,and the experimental verification was carried out.In this design,the microsphere array structure excites the higher-order cladding modes of the Gaussian beam,and the air cavity acts as the coupler of the Mach-Zehnder interferometer on the one hand and the Fabry-Perot interferometer on the other.The temperature sensitivity of the sensor is 160pm/℃,and the transverse load sensitivity is 124.6 pm/N.Compared with similar sensors,the sensor has the advantages of high sensitivity,low cost and strong practicability,and has broad market prospects.(2)In this paper,we demonstrated two high-sensitivity high-temperature sensors based on Michelson interferometers through comparative experiments.The interferometer structures all use microsphere arrays as excitation,and the difference is the number of microspheres.In the temperature range of 100-800℃,the highest sensitivity of the sensor is 0.139 nm/℃ and0.166 nm/℃,respectively.Experiments show that increasing the number of microspheres can improve temperature sensitivity while reducing the sensor size,which provides a new way to improve the performance of high-temperature fiber optic sensors.(3)In this paper,a single-mode optical fiber is used to design an ultra compact high-temperature optical fiber sensor based on a silicon microcap structure on the fiber end face through a simple fusion splicing technology.The sensor fused a single-mode optical fiber with a silicon microcap at one end to the“peanut”structure to construct a fiber-optic Michelson in-terferometer.The Michelson interferometer is more than ten times shorter.Through simulation,the optimal discharge parameters for fabricating the microcap and the length of the single-mode fiber are studied in detail.At the same time,the optical path model of the sensor is established by geometric optics.The experimental results show that the sensor shows good robustness in the double-cycle heating and cooling experiments of 100-900℃ and the long-term stability test of 900℃.It has good linearity in a large dynamic range,which is beneficial to practical temperature measurement and mass production.(4)In this paper,a transverse load and high temperature sensor based on the discrete cas-cade Vernier effect is designed for the first time.The two Fabry-Perot interferometers are com-posed of a hollow-core microtube and a polarization-maintaining photonic crystal fiber,which are connected by a single-mode fiber with a length of 1 m.By adjusting the lengths of the two Fabry-Perot interference cavities,a Vernier effect with a phase ratio nearly twice is achieved.After experimental tests,the transverse load sensitivity of the sensor has been improved by a maximum of 7.7 times to 5.84 nm/N?the temperature sensitivity is divided into 50-400℃ and400-900?The two interval discussions of C have been improved by 5.5 and 5.9 times,respec-tively,reaching 0.0689 nm/℃ and 0.1038 nm/℃.In addition,the two interferometers can be flexibly split and combined,and this sensor has great potential in sensing applications as well as quasi-distributed measurements.In conclusion,the research in this paper improves the performance of fiber optic sensors,especially high temperature fiber optic sensors,and deepens people’s understanding of high temperature fiber optic sensors.At the same time,these studies also have certain reference value for the future development of optical fiber sensors.
Keywords/Search Tags:Optical fiber sensor, Fabry-Perot interferometer, high temperature sensor, Vernier effect, Mach-Zehnder interferometer, Michelson interferometer
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