| The optical fiber temperature sensor uses optical fiber as the sensing element.The sensor has been widely studied by scholars due to its advantages of micro size,high sensitivity,stable performance,and simple structure.The polished D-type optical fiber is a new type of special optical fiber.The temperature-sensitive medium can be added to the Dtype area.The filling medium can directly modulate the optical information in the optical fiber,so the sensitivity of temperature measurement can be greatly improved.In this paper,an efficient D-type optical fiber processing device is improved and different liquid packaging methods are proposed,and the temperature sensing characteristics of the sensor filled with different medium materials are researched through experiments.The detailed works are as follows:1.Introducing the research status of multi-core optical fiber and polishing technology.The mode interference,the principle of the Mach-Zehnder interference,and transmission characteristics of the three-core fiber are theoretically analyzed,and the temperature sensing mechanism and self-image effect are illustrated.2.Establish a simulation model in the order of single-mode fiber,multi-mode fiber,three-core fiber,multi-mode fiber,and single-mode fiber.Then,simulate the energy transmission and optical field distribution evolution in the sensing structure to obtain the best coupling multi-mode fiber and D-type fiber length.The transmission spectra of the side-polished optical fiber structure filled with polydimethylsiloxane at various temperatures were simulated and calculated.It is concluded that the sensor has good temperature sensing characteristics,and the simulation sensitivity in the temperature range of 10-50 ℃ is-841 pm /℃,and the linearity can reach 0.9918.3.Describing the PDMS-filled fiber temperature sensor is fabricated based on the sidepolished SMF-MMF-TCF-MMF-SMF structure.An innovative method is proposed to improve the side-polished optical fiber experimental device,and the transmission loss of different optical fiber remaining thicknesses is analyzed and researched.The fabrication process of the side-polished optical fiber sensor with PDMS directly filled in the groove of the glass slide and PDMS with metal base added is illustrated.The factors affecting the performance of the sensor are analyzed and the maximum sensitivity of the PDMS-filled optical fiber sensor can reach-725.93pm/℃ after increasing the sensitivity.4.Proposing and fabricating an optical fiber structure with capillary packaging liquid based on the side-polished D-type optical fiber,and introducing the fabrication and packaging steps of the sensor.Temperature measurement experiments and stability research were carried out for sensors packaging of two liquids with different thermo-optic coefficients,ethanol and toluene.The performance of the side-polished optical fiber sensor based on liquid filling in this paper and the optical fiber temperature sensor in recent literature are compared and analyzed,the sensor prepared in this paper has the advantages of high sensitivity and simple fabrication. |
