Research On Optical Fiber Sensors Based On Multimode Interference Structures And Whispering Gallery Mode Microresonator

As the representative of Information and Communication Technology(ICT)in 21st century,the rise of Internet of Things has injected fresh vitality into the field of sensor.But the demands of reliability and accuracy for collecting sensing information put forward higher requirements for the sensor.Optical fiber sensing technology has always been the concern of researchers due to its fascinated advantages of nonelectrical,distributed,reliability,corrosion resistance,immune to radio frequency interference and electromagnetic interference.Driven by the development of Internet of Things,designing high performance and applicable optical fiber sensing systems has already became the main goal that researchers need to face together.The research work of this paper mainly lies in designing and manufacturing several types of optical fiber sensors for temperature and current sensing which are based on multimode interference structures and whispering gallery mode microresonator.And the working principle and sensing performance are studied experimentally combining with designing different sizes of sensors.The specific content of this paper can be divided into the following aspects:(1)The research background and basic principle of optical fiber sensing technology are expounded.And the research status of optical fiber temperature and current sensor are classified and summarized through literature research.(2)Based on Michelson interferometer,a novel core-mismatching fiber joint structure is manufactured by special fusion splicing method and applied for high temperature sensing with maximum sensitivity of 115.7 pm/?.This all-fiber high temperature sensor owns the advantages of compactness and low cost,and the repeatability is also good.(3)Based on high thermal expansion coefficient of UV-curing adhesive,an optical fiber temperature sensor with maximum sensitivity of 4.33 nm/?by combining the material and Fabry-Perot interferometer is manufactured.A positive correlation between the length of the filling material and temperature sensitivity is obtained,and the temperature sensor has excellent temperature measurement repeatability and stability.(4)Designing an optical fiber current sensor with maximum sensitivity of 25.5 nm/A~2by combing whispering gallery mode microresonator and Joule heating effect.By studying the effect on sensing performance of different sizes of microresonator and copper wire,it is found that the diameter of copper wire and hollow glass tube are negatively correlated to the current sensitivity,respectively.Besides,the sensor is stable and has high measurement accuracy.