The Research On Interferometric And Resonant Fiber Sensors Based On Single-mode Fiber

Optical fiber sensors have been widely used in petroleum,chemical,transportation,energy,metallurgy,medicine,etc.Due to their advantages of anti-electromagnetic interference,corrosion resistance,good electrical insulation and high sensitivity.field.In this thesis,several kinds of interference-mode and resonant-type fiber-optic sensors based on single-mode fiber are studied.The principle,preparation process and corresponding physical quantity measurement of these sensors are described.The details are as follows:1.The development history of fiber optic sensors and the status quo of fiber optic sensors in China are reviewed.The classification and characteristics of fiber optic sensors are introduced.The principle,application and several different preparation methods of the three sensors are introduced in detail.The Fabry-Perot interferometer and the Michelson interferometer are mainly introduced for the interferometric sensor,and the edgy wall mode resonant cavity is introduced for the resonant type.2.An optical fiber stress sensor based on misalignment fusion is proposed.The two etched single-mode fibers are misaligned to form an F-P cavity.When stress measurement is performed,the misalignment fusion causes a larger change in the cavity length,resulting in an increase in stress sensitivity,which can be increased from 2.39 pm/??to 7.75 pm/??.And the temperature sensitivity is measured at 1.2pm/°C,which effectively reduces the cross-sensitivity between strain and temperature.3.A multiple Michelson interferometer based on fiber inner beam splitter is proposed.The femtosecond laser is used to engrave two oblique beam splitters inside the single-mode fiber,and the fiber-cut end faces form three reflecting surfaces,which are combined to form three Michelson interferometers.It can be used to measure refractive index and temperature with sensitivity of-66 dB/RIU and 9.92pm/°C,respectively.4.A microsphere-based fiber-optic end-face whispering wall resonator is proposed.The device is welded to the NCF by SMF,and then the NCF is arc-discharged,and then the microspheres are glued at the end of the NCF.Using a microsphere of 97?m diameter,the quality factor of the WGM resonator is~2.9×10~3.The temperature sensitivity of the device sample was 21.34 pm/°C.The three traditional fiber optic sensors presented in this paper have the advantages of strong mechanical strength,ease of manufacture,compact size and low cost.