Research On Vibration Detecting Technology Of Eccentric Core Fiber

In recent years,the development of optical fiber sensing promoted the vibration testing technology innovation.In our life,a large number of optical fiber sensors are used in detection of vibration signals.Among them,eccentric optical fiber has a unique advantage than the traditional fiber because of its unique core structure.It has a stronger evanescent field and sensitive to the environment change.Thus show more outstanding advantages in terms of vibration sensor.Therefore,this paper studies the vibration detection technology based on eccentric optical fiber.First,the paper introduces the background and significance of the subject,and study the development of optical fiber sensing.The research status of eccentric optical fiber and vibration detection technology of china and abroad is analyzed.The outline of this article was decided and listed.Second,a theoretical model of the eccentric core fiber was established based on traditional optical transmission theory.By using conformal mapping,the asymmetric three-layer structure of the eccentric core fiber was converted into a three-layer structure of coaxial symmetry.The mode field characteristic s,evanescent characteristics,polarization characteristics of eccentric core optical fiber were analyzed.Optical model of eccentric core fiber was established by using Beam PROP module in Rsoft software.The transmission characteristics of eccentric optic al fiber are simulated by finite difference beam propagation analysis.Thirdly,the bending loss characteristics of eccentric optical fiber are studied deeply and the bending loss formula of the eccentric optical fiber is obtained.The relationship between bending loss and bending radius of the eccentric core fiber was analyzed.Meanwhile the relationship between bending loss and eccentricity distance change was obtained.The bending loss of the eccentric optical fiber in the 0o and 180o directions is simulated.The vibration sensor model was established according to bending characteristic of eccentric core fiber.We analyzed vibration sensor model by using ANASYS software,and the inherent frequency of model was obtained.Finally,the vibration detecting system was designed.The system consists of optical modules,photovoltaic modules and circuit modules.Each module components were selected and parameters were set.The vibration sensor working process was simulated.The simulation result shows that this sensor was better than traditional vibration sensors.Meanwhile,the vibration detecting system established a theoretical foundation for the application of the sensor.