Study On Fiber Optic Temperature/humidity Sensing Technology Based On F-P Interferometer And ARROW Structure

Fiber optic sensor is widely used in aerospace,metallurgy,medical and other fields because of its simple structure,high sensitivity and anti electromagnetic interference.The interferometric fiber optic sensor has high optical stability and large dynamic response range.It can work in high pressure,high temperature and strong corrosive environment for a long time.Over the past decade,scholars at home and abroad have focused on interferometric fiber optic sensors.The history of optical fiber sensors can be traced back to the 70s of last century.At that time,people began to realize that the optical fiber not only has the light transmission characteristics,but also itself can form a new basis for direct exchange of information,without any intermediate level can link the measured amount to the optical fiber in the optical fiber.In 1977,the United States Naval Institute began the implementation of the Foss(optical fiber sensor system)program chaired by Dr.Charles M and Davies,which is considered the date of the advent of optical fiber sensors.Because of its incomparable advantages and broad prospects for the development of conventional sensors,many countries have spared no effort to increase the research of optical fiber sensors,and many achievements have emerged.In recent years,sensors are developing in the direction of sensitivity,ingenuity,adaptability,intelligence and networking.As a new member of the sensor family,fiber optic sensor has the advantages of small size,light weight,anti electromagnetic interference,high sensitivity,measuring bandwidth,and detecting electronic devices and sensors can be far apart.With the introduction of new methods and new technologies,a large number of low-cost and high performance fiber sensors have come out,and the combination of optical fiber and other disciplines not only makes the optical fiber sensor improve the signal detection precision,transmission loss,signal processing,but also has a wider application domain.Based on the research of interferometric sensors and the preparation technology of sensors,two new optical fiber sensing structures for realizing humidity and temperature are designed and manufactured.The sensing structure consists of a Fabry Perot cavity and an anti resonant waveguide,which are composed of quartz tube,fiber grating and polymer film.The specific content of our work is shown as following:In theoretical research,(1)the interference and sensing mechanism of the F-P cavity are analyzed and discussed,and the sensitivity of the interference spectrum and sensing is discussed in combination with the new F-P cavity structure proposed in this paper.(2)using MATLAB tools to analyze the relationship between parameters and sensitivity of sensor phase and spectrum in sensor.(3)the light transmitting characteristics and resonance principle of ARROW structure are summarized and summarized.(4)the transmission mode of sensor samples with different parameters is discussed in detail by using COMSOL finite element analysis software.In experimental research,(1)a temperature and humidity dual parameter sensor based on Fabry Perot resonance structure is proposed.The sensing principle is analyzed and the experimental research is carried out.The experimental data are measured on the humidity and temperature characteristics respectively,and the double parameter simultaneous measurement is realized with the optical fiber grating compensation mechanism.The reflected light of the surface of the Nafion polymer film and the reflected light of the fiber end face form the interference spectrum,and the adjustable function of the interference spectrum is realized by the adjustable position of the optical fiber in the quartz tube.The experimental results show that the Nafion film is sensitive to temperature and humidity,and the temperature sensitivity is 2.71nm/~o C,and the humidity sensitivity is 3.78nm/RH%.(2)a humidity insensitive temperature sensor based on anti resonant reflective optical waveguide is proposed.The interference spectrum in the structure of the coupling of quartz capillary and optical fiber in its structure is similar to the principle of the interferon interferometry,and the polymer film is used as a temperature sensitive material,and then the moisture insensitive isolation effect is achieved through the metal coating technology.The experimental results show that the PDMS film has a good response to the temperature,and the linear sensitivity is201pm/~o C at a specific temperature range,and it has good stability.