Sensor Research Of Dual Parameter Measurement Based On Trapezoid Structure Single-mode Fiber

With the progress of the times,people need to be more and more sensitive to the external environment,and a variety of sensors came into being.Because of its advantages such as high sensitivity,small size and being able to adapt to the harsh external environment,optical fiber sensor is favored in the sensing field and has been widely concerned and studied.As two indispensable parameters in the external environment,temperature and refractive index are of great importance.Based on the interference theory of light,this paper analyzes and studies the coherent light produced by the core mismatch in the optical fiber.Combined with the theory of Mach-Zehnder interference(MZI)optical fiber sensor,three kinds of optical fiber sensors with temperature and refractive index measured at the same time are researched and manufactured by using trapezoid structure and spherical structure,eccentric core structure and fiber Bragg grating(FBG)cascade.The main contents and research results of this paper are as follows:1.This paper summarizes the research significance and background of optical fiber sensor,illustrates several interference sensors based on interference principle,and summarizes the research status of several special structures(spherical structure,eccentric core structure,concave cone structure,S cone structure,ring structure,etc.).2.The fabrication process of the trapezoid structure is proposed and described,and the principle of the trapezoid structure as the coupling structure of the optical fiber sensor is analyzed.Trapezoid structure is simple,low loss,low cost,and has a wide application prospect in the field of optical fiber sensing.3.According to the trapezoid structure and the spherical structure,a single mode optical fiber sensor based on the cascade of the spherical structure and the trapezoid structure is proposed.The spherical structure and the trapezoid structure are used as the coupling structure of the MZI optical fiber sensor,which plays the role of light splitting and coupling,and the middle section SMF is used as the sensing area.The experimental results show that the two interference troughs and the sensitivity to refractive index of the sensor are-35.93nm/RIU and-51.14nm/RIU,respectively,and their temperature sensitivity are 0.05nm/? and 0.04nm/?,respectively.According to the theory of two parameter simultaneous measurement,the sensor can measure the temperature and refractive index at the same time.4.According to the trapezoid structure and the eccentric core structure,singlemode optical fiber sensor based on the trapezoid eccentric core structure is proposed.The trapezoid eccentric core structure is the coupling structure of MZI optical fiber sensor,which plays the role of light splitting and coupling,and the middle section SMF is the sensing area.The experimental results show that the two interference troughs and the sensitivity to refractive index of the sensor are-35.93nm/RIU and-51.14nm/RIU,respectively,and their temperature sensitivity are 0.05nm/? and0.04nm/?.According to the theory of simultaneous measurement of two parameters,the sensor can measure two parameters at the same time.5.According to the trapezoid structure and fiber Bragg grating,a kind of transmission single mode fiber sensor based on the cascade of trapezoid structure and Bragg grating is proposed.Trapezoid structure is the coupling structure of MZI fiber sensor,which plays the role of light splitting and coupling,and the middle section SMF and FBG are the sensing areas.The temperature sensitivity of trapezoidal MZI and FBG is 0.10nm/? and 0.01nm/? respectively.The refractive index sensitivity of trapezoidal MZI is-101.30nm/RIU.According to the theory of simultaneous measurement of two parameters,the sensor can measure two parameters simultaneously.