Research On High Sensitivity Sensor Based On All Fiber Michelson Interferomrter

The detection of salinity is very important for marine resources development, agricultural environment monitoring and management,marine climate prediction, mineral exploration, and military applications,etc.At present, the salinity measurement methods mainly including conductivity method, gravity method, refractive index method, plasma resonance method, remote sensing microwave method and optical fiber sensing method have developed relatively mature .However, with the continuous development of the demand for salinity detection in various fields, the demand for high precision, small volume and large range of salinity sensors is urgent.All fiber Michelson interferometer is a kind of high precision fiber optic sensor, which has been developed in recent years. The principle of sensing comes from light interference in the same optical fibers, which make sensor with high integration, small size and high sensitivity.Compared with ordinary machinery sensors and electronic sensors, fiber Michelson interferometer has its unique in the analysis of liquid concentration and ingredient.In this paper, the salinity of the full optical fiber Michelson interferometer sensors as the research target.Compared with the existing fiber grating refractive sensor,the sensor has the characteristics of high sensitivity,simple structive,low cost and easy realization.The structure of the sensor and sensing properties were studied systematically. The main work arelisted as follows:1.Several main salinity detection technologieswere introduced.The present situation of salinity sensor at home and abroad were summarized.The research status of salinity measurement in the field of optical sensing were discusses.What's more, the development of optical fiber Michelson interferometer liquid concentration sensor was summarized.2 .The fiber Michelson interferometer sensor was theoretically derived. What's more, the sensing principles of liquid refractive index,stress and temperature were description in detail.3.The all fiber Mach-Zehnder interferometer was used as high temperature detection. From the optical fiber Mach-Zehnder interferometer temperature sensing principle, the experiment showed that the maximum temperature of high temperature sensing property was 900?. The sensor sensitivity was 22 pm/?.4.The liquid concentration and temperature were researched based on the structure of optical fiber Michelson interferometer salinity sensor.The temperature and liquid concentration sensing properties were studied.5. The study of optical fiber Michelson interferometric coated with polyimide film mainly included theoretical and experimental research on the fiber stress and salinity sensing characteristics before and after coating.The experimental result showed that under the condition of small displacement, the stress of the thin core fiber was obvious. too. The sensitive of salinity was 19.268pm/%.Compared with the two chapters 4 and 5, it showed that high precision structure after coating the salinity of the sensor sensitivity is higher than before the film's conclusion. In addition, the sensor can also be applied in the field of biomedical and environmental monitoring except the detection of seawater salinity.